Professor David Craig (1919-2015), theoretical chemist

Professor David CraigPresident of the Australian Academy of Science 1990-94.

Professor David Craig was born in 1919 in Sydney. He completed a BSc(Hons) at the University of Sydney in 1940 and an MSc in 1941. From 1942 to 1944, his scientific career was interrupted by war service and in 1944 he returned to the University of Sydney as a lecturer in physical chemistry. In 1946 Craig moved to University College, London, where he was a Turner and Newall Research Fellow. On completion of his PhD in 1949 he was appointed lecturer at University College until 1952. In 1952 Craig returned to the University of Sydney to be the first Professor of Physical Chemistry. In 1956 he went back to University College, London as Professor of Theoretical Chemistry. In 1967 Craig came back to Australia when he was appointed Foundation Professor of Physical and Theoretical Chemistry at the Research School of Chemistry, Australian National University (ANU), a position he held until his retirement in 1984. At the ANU he served as Dean of the Research School of Chemistry from 1970 to 1973 and was an Emeritus Professor there since 1984. Professor Craig passed away in July 2015.

Interviewed by Professor Bob Crompton in1998.


The early road towards science

David, perhaps you could tell us something about your parents and where you were born.

I had a middle-of-the-road upbringing. My father was a Manchester man who had a very difficult early life. His father died when he was 18 months old, but the father had taken out an insurance policy under which the four children, of which he was the youngest, would all be educated at Cheadle Hulme Grammar School. That is a boarding school close to Manchester, in much the same class as Manchester Grammar. So the children got a good education, and they did very well there.

My father took articles and learned to be an accountant with a Manchester firm. But in 1911, at age 24, he emigrated to Australia for a warmer climate because of his antrum and sinus trouble. Bit by bit he drew the rest of his family out after him, and then in 1915 my mother came out in a boat called the Suevic – safely, despite a trip round the Cape of Good Hope with threats of submarines. My parents were married in Hobart in 1915.

My father teamed up in a firm of accountants called Craig and Fraser, in Sydney, and then went into business in a middle-sized firm called James Sandy and Co., of which he became managing director. The firm manufactured paint and shop-fitting requirements at Redfern and retailed them from a show-room in George Street, Sydney, close to where Wynyard Station is now.

I was born in 1919, at Roseville. My primary education was at Knox Grammar School, at Warrawee on the North Shore line of Sydney, and the secondary part of my education was at Shore – Sydney Church of England Grammar School – in North Sydney. We had a good teaching staff. The headmaster, Mr Robson, was the mathematics master – a Brigade Major in the First World War, very stern but also a very good mathematician. The physics teacher was Mr Fisher, and in chemistry we had E J Clinch, who was really a very good teacher. Unusually, he already knew about resonance and the then modern theory of the valence-bond.

Your own work later has been at the intersection of physics and chemistry, hasn’t it? We never know whether to call it chemical physics or physical chemistry.

I’ve always tried to bridge those two. That’s where my interests have been, throughout.

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Studying covalent bonds

When did you go to Sydney University?

I began in 1937 and had the standard four years plus honours course. It didn’t cost my family anything much because like quite a few people I had an Exhibition, which was a publicly funded form of support, and I lived at home. After three years as an undergraduate I was taken on as a student by D P Mellor, who had just come back from Caltech (California Institute of Technology) with the wonderful ‘message as given by St Pauling’ and was full of fire. Linus Pauling had just a few years before that published his famous work on the nature of chemical bonding, particularly covalent binding. By the time that Mellor joined him, he’d got interested in the study of bond type, through magneto-chemistry. You take a standard tube and you pack it with the material of interest, hang it in front of an electromagnet and find what apparent change of mass there is when you switch the magnet on. You can interpret these measurements of susceptibility in terms of the nature of the binding in transition metal coordination complexes. If you’ve got nickel surrounded by four atoms, you can in some cases decide whether they’re square or tetrahedral.

Pauling rationalised the relationship between magneto-chemistry, magnetic susceptibility and bond type in terms of the orbitals that were being occupied in the two sorts of binding. Depending on that occupancy you get a different magnetic property – unpaired electrons in the one case and no unpaired electrons in the other, if we’re talking about nickel. So just by a simple measurement of whether it is paramagnetic or not you can, in favourable cases, discover what the bonds are doing. Mellor and I did that in cobalt, in which a somewhat similar situation applies, with some minor differences.

Pauling was a very interesting man. I saw quite a bit of him later in my career because I got to know his son, Peter Pauling, when Peter worked on the staff at University College, London as a crystallographer. He was one of the first to use computers in X-ray crystal analysis. The father would visit to see him and also to see Christopher Ingold, whom we’ll talk about a bit later on. I have a photograph of Pauling taken in 1973 when he visited the Research School of Chemistry in the ANU.

Later in this initial time at Sydney University, you had your introduction to quantum mechanics, didn’t you?

Yes. It had been discovered in ’26 but in Sydney the message was just filtering through and it was a great novelty. In physics they had Dick Makinson, who was a very able physicist and had grasped quantum mechanics better than others, and in chemistry, Allan Maccoll – who was a great buddy of mine – had spent a vacation working through Dirac’s first book, which is formidable, terribly difficult, and had read other books as well. He gave us a course of lectures in my last year, and got me interested too. Together we worked through a couple of books, doing the best we could with them, trying to get the message.

He was only a few years older than you, wasn’t he, and doing an MSc at the time you were doing honours?

Yes. He’d done a double degree, in maths and chemistry. He later got involved in chemical kinetics rather than theory, but kept both alive. He was the first of us to go to University College, in 1945.

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War service, firstly in Australia

Those early days of yours resulted in four or five papers, I think, and several prizes on the way. Your honours year ended after war had begun. Did you join up then?

I finished my honours in about November 1940, and I worked on an MSc over the long vacation and into the early part of ’41. Then the Sydney University Regiment, of which I had been a member for some time, went into camp for about three months and while I was there the rules were varied so that people in reserved occupations – as most of us were – were allowed to enlist in the AIF, at first for service in Australia only but later overseas as well.

After that happened, the Regiment was to be disbanded and the commanding officer, Colonel Stacy, had to decide what to do with his officers. Some went off to anti-aircraft batteries because of the threat already of Japanese bombing. I thought that the thing to do was to try and serve in something in which my scientific training would be useful, and so I went along to talk to Commander Quince, of the Anti-Submarine Unit, who had been a master at Knox when I was there. The Unit was dealing with ASDIC, the use of sound waves to locate submarines, so he tested me in detecting changes of pitch between the reflected and the outgoing sonar beams, which I found very easy. But just as I was leaving he said, ‘Oh well, you’d better do the Ishihara test.’ Being colour-blind I failed the test disastrously, so that was the end of my aspirations to get into the Navy.

I would have thought that a hearing test was far more important!

However, Colonel Stacy, of the University Regiment, had been commander of the 1st Australian Battalion and was an old friend of General Sir Iven Mackay, formerly CO of the 4th Australian Battalion. They had been together on Gallipoli, in the First World War. And just at this time Mackay came back from the Middle East and wrote to Stacy that he was looking for an ADC. Stacy packed me off to Melbourne to try my luck, Mackay took me on and I worked with him for quite a bit.

After the bombing of Darwin we had to go up to see just what had happened. We took off from Mallala airport, north of Adelaide, in an RAAF Avro Anson – a rather ancient pre-war bomber with two engines and only a slight range so that we kept constantly coming down. We were refuelled at funny little airstrips, often by Aboriginals who were very good and quick at it. On we went, step by step, until towards the end of the first day, when darkness was coming down and we were still nowhere near Darwin, the pilot lost his way. There were no radio direction-finding aids available to him and he literally couldn’t find Tennant Creek. We were weaving about, looking for the line of the north-south road, when suddenly he spotted a little group of dwellings and made a landing on a dirt road at right-angles to the north-south road. The plane ran into a ditch but nobody was hurt, so we got out and wondered what to do. Well, in about 20 minutes there was a dust cloud in the distance. In the dusk we watched this thing grow and it turned out to be a Dodge open car of about 1925 vintage, in which there were six very stalwart gents with shotguns. It turned out that the postmistress at old Tennant Creek had sent a message to new Tennant Creek saying the Japanese had landed!

We were taken on from there in a Hudson bomber, through Daly Waters to Darwin, three or four days after the worst of the bombing. We could see all the ships sunk and there were fires still burning in some places.

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To New Guinea and back to Sydney

You have a photograph there showing you in New Guinea. What was that about?

Well, later that year we went to New Guinea, this time flying from Townsville to Port Moresby in a Sunderland flying-boat, a very slow aircraft of about 90 knots so that the journey took about four and a half hours. One very interesting trip we made was to Wau, early in 1943 after the action there by the 17th Brigade to repel the Japanese from Crystal Creek. The New Guineans who helped in that had been organised in units, and the photograph shows them with their commander, lined up to have medals presented to them by General Sir Iven Mackay, accompanied by Brigadier Moten, the commander of the 17th Brigade, the Brigade Major of the 17th Brigade and the commander of the local group of ANGAU, the Australian New Guinea Army Unit. I am on the extreme right.

Then your war effort shifted to Sydney, did it?

Technically I was still in reserved occupations, so the Manpower Service arranged for me to return to the University of Sydney, where Professor Fawsitt, the Professor of Chemistry, was looking for new staff. I was mainly lecturing but I did do some work there towards the scientific war effort with Adrien Albert, on the amino-acridines. These bacteriostatic agents inhibit the growth and reproduction of bacteria. Acridine orange was the most famous of them. Albert was developing new ones which were more powerful and which didn’t stain – the acridine orange was a shocker for staining clothes and so on – and he needed someone to work on their ionisation properties and their spectroscopy. So I was lined up to do that with him.

We were very under-equipped. There was no spectrophotometer at all in the University and I had to go and use one at the Royal North Shore Hospital, where Dr Rudi Lemberg, working on the blood pigments – verdohaemochromogen and so on – was good enough to let us use his instrument, on the strict condition I cleaned it up carefully at the end. So we worked on that, and I published a paper on it. But that was my sole contribution to the scientific war effort.

I was back in Sydney in time for the academic session which started in March ’44, when help was needed to teach the large classes that were being formed because quite a few returned soldiers were enrolling by then.

That would have been an interesting mix: raw 17- and 18-year-olds with these people who’d had a lot of experience and had a real drive to get on.

Yes, and very riotous and rowdy the classes were, too. One night, at a meeting of the Chemical Society, a fellow got loose with a fire extinguisher, the old foam type, and was squirting it round everywhere.

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At University College, London, for the first time

That stint on staff at the University of Sydney didn’t last long, did it?

No. In the next year, 1945, the first of the Turner and Newall Research Fellowships were advertised for the UK. Allan Maccoll got one and went to work at University College, London with Ingold. The next year, when I applied, the ones on offer were at University College and Liverpool. I had the offer from Liverpool but in the end had another offer from London, which I accepted because for me there was just nothing that could equal the chance to work with Ingold in his department.

During the war the department had been moved from London to Aberystwyth, in Wales. After the worst of the bombing was over, in ’43, it had come back and now Ingold was building it up again. Already there were at least 60 or 70 postgrads there, and that grew very quickly to about 100. He had a great reputation.

Was he a knight already, David?

No, he was knighted after being President of the Chemical Society, which was a few years after that.

And you were one of many Australians seeking that opportunity just after the war?

Yes, absolutely. In 1945 there had been the first departure of people who had had their overseas training delayed by the war, and ’46 was the second major departure. We went on a boat called the Waiwera, which was a cargo steamer really, but with quite a few berths for passengers on board. It was packed with postdocs or postgraduate student hopefuls, of whom you will know Gordon Ada, Douglas Waterhouse and also Edwin Salpeter, who went first to work with Peierls in Birmingham, on infinities in quantum electrodynamics, and then to the US to work with Hans Bethe at Cornell, where he has stayed the whole of his working life. He was made an Honorary Fellow of this Academy.

How did you find London and University College, so soon after the end of the war?

London itself was cleared of a lot of the rubble but very little building had been done, and you could see the nature of the damage – houses were split in two and you could see torn wallpaper inside the rooms, and the baths and so on. An extraordinary sight. The streets had weeds growing in them – it was a scene of desolation. And the College itself had been badly bombed in two big raids in ’40 and ’41, probably because it was close to Euston Station, close to Kings Cross. There was huge destruction in the library – many of their most valuable manuscripts had been sent off to Wales and were safe, but the ordinary, run-of-the-mill science serials had largely gone and had to be replaced, at great expense. Although the rubble had been cleared, it hadn’t been replaced by anything and part of the library was just a blank space.

Chemical Engineering had been flattened and a lot of the other buildings had been damaged, though Physics and Chemistry had escaped, fortunately. But it was really a pretty pathetic sight and the buildings hadn’t been properly maintained inside. The chemistry laboratories were really primitive and dirty, but there was a great spirit.

What about equipment?

Oh, that was quite good. It had gone the double journey to Wales and back. But in addition to that, big firms like ICI had been very generous in building the College up and during my time we got lots more equipment, usually from industry. So it was really in good shape.

But the main thing was the extraordinary vitality and the total research orientation of the place, which was something that I hadn’t really experienced with intensity before. Everybody really had their heads down. And the teaching loads on staff were very light. In my time I think I gave 30 lectures a year, which was an average load and yet was nothing compared with today’s load.

Who were some of the people you met at University College?

On arriving I was astonished to see people like J B S Haldane in the common room, holding court with his acolytes – a very interesting man – and J Z Young, about whom I remember an allegedly true story. J Z Young worked on the nervous system of octopuses and the way they responded to sounds. So, in pursuit of his research, he applied to the Science Research Council for a ‘digital tone generator’. When, in due course, this request was approved, he bought himself a piano! Well, that was one way of generating tones. Andrade was also there, and D R Bates and Harrie Massey.

You have told me that your PhD took two and a bit years. It’s enormously to your credit that, immediately on conclusion of your PhD, you were appointed to the staff of University College.

Well, I think they were pretty hard up for staff. I don’t feel all that flattered. Anyway, I liked being appointed to the staff: it was security. My fellowship paid six hundred a year, which wasn’t all that bad, but I was getting married at about that time and the little extra came in handy.

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Applying molecular orbital theory

What was your main scientific interest during that spell in University College?

When I was doing my doctorate, knowing the interest in the department in benzene I worked on the theory of the excited states of benzene – although they had been experimentally characterised to a degree, theoretically there was no proper account of them. First I enlarged the existing method of valence-bonds, and added a different kind of structure in which there were separated plus and minus charges as well as ordinary covalent bonds. I got from that a reasonable picture of the excited levels of benzene, of which two by that time had been roughly characterised so I had a kind of test.

But then I got interested in the serious discrepancy between that theoretical picture of benzene and the molecular orbital picture which had been developed beforehand by Mulliken, amongst others. Working through some work that had been done in 1938 on the molecular orbital theory in which the parameters were all calculated instead of being empirically fitted to experiment, as was the pattern of the time, I was struck that there was something very odd about the results. The separations between the states were sometimes smaller than the coupling integrals between them, so that it really made no sense to claim that those states were physically real. What you had to do was to work it out again, including all that interaction between configurations, and that’s what started me off on the business of configuration interaction. Once that was done, it all began to fit into place – not with great numerical precision, but with agreement in the ordering of the states, which was the first thing you had to look for.

Next I had an interesting, enjoyable period of working with Ian Ross, who was one of my first PhD students and also had worked with me a bit in Sydney so we were very comfortable working together. We wanted to improve the integrals that went into these computations – technically it’s the change from two carbon centres to three and four carbon centres that you’ve got to accommodate. Then I had a letter from Robert Parr, an American who was working with Mulliken in Chicago, saying that they were working with these integrals and he’d got a few himself, and would we like to team up and do a joint trans-Atlantic effort, in which we’d recalculate the whole business, using Parr’s integrals and ours? We agreed to do that. I’d never met him, didn’t meet him for 10 years, but we had a good correspondence and published a joint paper which really for the first time got sensible agreement between theory and experiment.

To extract the roots of a six by six determinant for this work, as we had to do, was a formidable task using the mechanical calculators of the time and was really a full day’s work. And to allow for mistakes it all had to be done twice – we did it once in London, and Parr repeated everything in the US before we could accept that it was right. Now, of course, we can do it in microseconds.

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Some stimulating interactions with fellow scientists

We’ll come back later to what computers have done for your field. But first would you like to tell us about your interaction with Teller? It began while you were at University College and continued on and off for some time, I believe.

Yes, that’s right. Edward Teller had been a refugee from Europe in about 1933. Donnan and Ingold, at University College, had given him facilities and accommodation, and Teller in that time had done his famous work with Jahn, the two papers on the Jahn-Teller effect. Because he’d published a paper with Herzberg in ’33 about the interaction of vibrations and electronic motion and that was involved in what Ingold was doing with benzene, there was a natural affinity there and Teller was a theoretical adviser to Ingold and influenced a lot of what went into those famous benzene papers. There was a continuing connection after Teller left and for a long time he was a frequent visitor to the department. I met him on one of those visits.

I’d been working – I suppose really because of Ingold’s interest – on this very problem of vibrational electronic interaction in benzene, as an element in the structure or the spectrum you observe. The problem was not the identification of it but the magnitude, and I had a little model that gave me a magnitude and made a certain amount of sense. When I talked to Teller about it, he was much interested and suggested that I go to work with him in Chicago, as I guess it was at that time, saying that I could work with Mulliken too. I thought it was a bit rich but I’d better try, but to get there I had to apply for a Harkness Fellowship. I didn’t get one, so the whole thing ran into the sand, but I have had many contacts with Teller over the years.

Teller was a wonderful man for discussing a problem with, even though it wasn’t at the top of his mind. We were working on naphthalene at one stage at UC but couldn’t make head nor tail of the problem we encountered. When Teller turned up I told him about it, and he said, ‘Oh, what’s naphthalene again?’ I drew him a picture on the blackboard and said what we thought the orbitals were like, and the electron eigenfunctions and so on. I said we couldn’t really determine which way the first transition would run, along the big axis or the small. He waggled his leg, as he always did sitting on the edge of the table, thinking about it, and in the end he produced an answer which actually was not right but it was brilliant to see the man’s mind ticking over in something that was foreign to him. I don’t suppose he’d thought about that for donkey’s years.

He was quite a forceful character, wasn’t he?

Oh yes. He and Ingold had wonderful discussions and occasionally the junior people like me would be invited along to dinner with the two of them. Of course, we didn’t get a word in while they were batting ideas about. It was the same with Pauling. He and Ingold used to dine together and take us along – wonderful experience. They’d be talking about things that I’d never heard of at the time, such as the Hall effect. Well, I didn’t think Ingold would know what it was. Pauling I’m sure would have, but there they were batting it back and forth.

You said that Teller worked with Herzberg quite a bit. Did you ever meet Herzberg?

Oh yes. Herzberg was a frequent visitor at the College also. He was a supremely good experimental spectroscopist and he was much helped by Teller in the theory. I think Teller was a constant consultant for him throughout many years before Teller got into the nuclear field so deeply.

This was about the time of your second interaction with Maccoll, too, wasn’t it? Was he already on staff at University College then?

Not quite. He had just about finished his PhD on gas kinetics, but he was on the staff before I was and so we were able to get together and work on some of these problems that we’d worked on in Sydney, particularly on what were called the nonbenzenoid aromatic molecules.

This is a class of aromatics, of which benzene is the father and naphthalene and anthracene are the next in line. What distinguishes them is that you’ve got alternating double and single bonds round the rings. There are other systems with that property which are not aromatic, for some reason. For example, there’s the molecule that has two five-membered rings, called pentalene, with alternating double and single bonds, but at that time it had not been made. People had tried very hard to make it. Another one, called heptalene, has two seven-membered rings, same property. So we got together to work on this problem and we found ways of making distinctions between it and the regular aromatics in terms of symmetry properties.

Purely theoretical?

Purely theoretical, yes. We discovered that whereas the ground state of the normal aromatics was totally symmetrical in the symmetry group, the other ones were not. So if you could find a rule for saying which would go this way and which would go that, you would enable people to say straight off, without trying, ‘Well, this is a pseudo-aromatic. It won’t be easy to make.’ We did put out some rules which worked quite well for a few years, but then an exception was found and that was that. We had the pleasant experience later on of people successfully making these molecules and finding they really were very unstable – decomposing very quickly.

I have here a picture of Allan Maccoll and me that was taken probably in Bologna, with Christopher Ingold and Angelo Mangini, one of the great fathers of post-war Italian chemistry. There was a very interesting connection between Mangini and Ingold. Italian chemistry had suffered dreadfully during the war. The bombing in Bologna was formidable – the railway yards were blown to smithereens – so after the war they had almost nothing. But under the Marshall Plan, by which Europe could be, to a degree, built up again with American funds, with Ingold’s support Mangini had succeeded in getting a very good swag of equipment. There was a strong friendship between them. When I first got to Bologna, the first thing that I saw was great piles of equipment in boxes, under the Marshall Plan, not yet unpacked.

Ingold and I went together on that occasion. We flew to Milan, and Mangini had sent his driver and his large, grand Fiat car to meet us. We set off back to Bologna, through villages, up and down – they didn’t have the Autostrada in those days. Our driver had driven in the Mille Miglia, the great motor race of those days, and he was mad, wild. Up and down these hills, with the local inhabitants scattering to right and left. When we finally arrived in Bologna he said, ‘Oh gee, I said to the boss I’d be here five minutes ago, and we’ve only just made it now.’

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Moving on with spectroscopy

After a while your students at University College were doing experiments that were all spectroscopy, weren’t they?

Yes, and at that stage I was doing a bit of experimental spectroscopy myself, sharing the work. We got into the business of identifying spectroscopic transitions between two triplet states. In benzene, for example, normally the only states you can see are singlet states – that gives you the ordinary spectrum. But if you get it at low temperatures and you irradiate hard with ultraviolet, some of the molecules will slip into a triplet state. While they are in that state you can measure the spectrum again, and that’s what Ian Ross and I began doing at that stage. We had interesting contacts at that time with Michael Kasha, who was a student of G N Lewis in Caltech – again a US connection in our work.

Our early work with crystals has its own bit of interest. To get decent crystal spectra you had to have very cold conditions. Liquid nitrogen was available to us but not cold enough; you could still see too much vibrational excitation. So we decided the only thing to do was to go for liquid hydrogen – liquid helium was not available – and we had a special Dewar flask constructed for it in the workshops at UCL. There were two Dewars, one for use in the spectra, to cool the crystal down, and the other just to carry the stuff round. We discovered that F E Simon at Oxford was making liquid hydrogen in their laboratories and was willing to supply it, so Peter Hobbins, who was my student working on this, took a Dewar flask up on the train and brought it back, several times. But then, to our dismay, there was a huge explosion in the Oxford hydrogen generator – caused by condensation of oxygen from the atmosphere on the surface of the hydrogen, after which the obvious happened. But we’d been carrying this stuff up and down on the public trains for months!

It’s remarkable, then, that we’re having this interview.

Yes. What is most surprising is that Peter Hobbins survived all the hard work of getting it there and back. And it worked to a degree. Before this terrible explosion we’d got quite a few results, but that was the end because hydrogen was recognised to be just too dangerous. So no more really low temperatures until helium came along.

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Marriage and family

You mentioned that you were getting married at about the time you were appointed to the staff of University College. This is probably the time to say something about your marriage and family. Was your wife-to-be an Australian?

Yes. I’d met her in about 1944, on a train between Sydney and Nowra. We’d been on a hike to the Shoalhaven. Meeting her was the best thing that ever happened to me. Then she came and joined me in England in ’48, and we were married in Reading, in Caversham. On making our decision we went to see the parson, and I had to explain to him that although I’d been brought up in a Church of England school and during the war on my ‘meat-ticket’ I’d had ‘C of E’ written – in case the worst happened – I really was not a religious type of person. When he said that was all right, I went on, ‘But I think we’d like to see the church some time.’ He said, ‘Oh, that should be possible. What about 11 o’clock on Sunday morning for morning service?'

We have four children, of whom Andrew is the eldest, born in August 1949. He was at school in England and later did engineering at the University of Sydney and also environmental science at Murdoch. He now combines those, as an environmental engineer managing a fire control program in the extreme north of Western Australia, with a view to encouraging desirable species and discouraging weeds.

Our second, Hugh, is an academic in the Department of English at the University of Newcastle. He works in part on the computer recognition of authorship, taking a piece of writing and analysing the use and frequency of words in it, in order to compare it with authentic samples writing by a known author such as, say, Jonson or Shakespeare and say that it certainly – or probably – is or is not by them.

Number three is our daughter, who is a doctor in Sydney, married to a solicitor. She practises medicine as much as she can with three children. And our fourth is a senior lecturer in the Department of History in the ANU, so we have two out of four academics. We’re up to seven grandchildren now.

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A new Chair in Sydney, and again to London

I think you were only at University College for another couple of years before you got a call back to Sydney.

Yes. In Sydney the Council had decided to change the structure of the Department of Chemistry – which had hitherto had two Chairs, Organic and Inorganic – by calling it a School and adding a Chair in Physical Chemistry. I came out to be their first Professor of Physical Chemistry in ’52, I suppose that was. It was a very different department, with quite a bit of equipment – nothing like what I’d been used to in London but it was a good deal better place to work in by then – and very good people on the staff, with a strong research orientation. That’s been a feature of Sydney.

You got your Chair in Sydney when you were still a very young man, about 32. Arthur Birch also took up a corresponding Chair. Was that your first encounter?

Yes, because he’d left Sydney for England well before the war, probably in 1937. We got on famously together in Sydney and we were quite a useful combination, with a few battles to fight. Equipment money was ludicrously short – you had to beg for a few hundred pounds. We begged together and we got a bit of money, but not enough really. It was an interesting school, with Le Fèvre as head and Professor of Inorganic. Arthur was Organic and I was Physical.

I suppose you were dealing mainly with theory by now.

Well yes. I was not doing experiments but I was still running them. One very interesting project was again on naphthalene because we were still concerned to identify experimentally what the excited states were. We got the idea that if we could make a vapour absorption spectrum we could perhaps detect from the nature of the contours of the bands what the directional properties were. It had been done for diatomics, where it was a well-known method. I had a very able and interesting student called Max Redies, who had been in Sydney working with Thomas Iredale, and he was a rather chubby, tubby man. We found that the only way we could get enough vapour pressure of naphthalene in the spectrometer, because we didn’t have a heated tube, was to warm the whole room. So we warmed the entire room to 35 degrees Celsius or more and poor old Max Redies was in a terrible state – he was almost liquid!

We were fortunate to have a Hilger large-quartz spectrograph, which I think Iredale had got years before. Its resolution was just enough to detect a difference in the contours of two of the sets of bands. Armed with those few spectra I went back later to London, where we got a proper spectrometer onto it and that then resolved them comfortably.

This stay in Sydney was fairly short, wasn’t it?

Yes. I heard from Ingold that he would like to get me back in his department, having already got Nyholm back from Sydney Technical College. They had everything that opened and shut in equipment, and an excellent supply of research students and postdocs – it was irresistible. So I went back in ’56. By then London had been greatly rebuilt – despite great blanks in South London – and the College was largely restored. It was a different world to work in. The library was still a bit deficient, but much had been done to restore it and we had libraries close by, such as at the University of London.

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In the thick of crystals

What was the focus of your work by that time?

By then I was in the thick of crystals. Liquid helium was easily available and had transformed the whole crystal spectroscopy scene. You could get fine structure that was invisible otherwise. I got some theory going, because in crystals you find that spectral transitions that are single in the molecule get split into two or four separate components, and the magnitude of that splitting can tell you what the characteristic of the transition was, its transition moment. It’s a very important number. This Davydov splitting was named for a Russian who had done the first work on it, showing that it would exist, but we couldn’t get the magnitudes of the intensities right. We got the idea that you had to allow not only for the splitting but for the effect of the crystal field on the mixing of what in the free molecule were separate transitions. They got melded and merged in the crystal. Once you do that, in a certain class of transition the intensities come right. For very weak transitions we had to use a different trick theoretically, but we got to the bottom of all of that.

What was your collaboration with E A Power?

Well, when you work out the interaction between the transition dipoles in the crystal, which underlies the splitting, you’ve got to find out the dipole-dipole interaction sums. But that raises a very tricky problem because, as is well known in static dipoles in three-dimensional arrays, the value of the sum depends on the surface shape: it’s different for a sphere, an ellipsoid and so on. Edwin Power, who was an applied mathematician at University College, already knew that if you used retardation in the potentials – that is, allowing for the speed of propagation of the signal from one dipole to another – then convergence looked possible. The sum wouldn’t be shape-dependent. So Power and I worked on that problem and elaborations of it, beyond just dipole sums into the interaction of optically active molecules, which was the main focus of our work, and also on the theory of the dispersion interaction at long range. That two-way collaboration worked out very well and our association has continued, but the irony was that the problem that I’d first discussed with him turned out to have nothing whatever to do with retardation.

Another colleague, the Sri Lankan Thirunamachandran, began with you round about that time too.

Yes. (He accepts just Thiru as a name.) He was a member of staff in the University of Ceylon, as it was then called, and came to do a PhD with me. In those days, because you couldn’t get a PhD in Ceylon you could be put on the staff without a PhD, so he’d had some research experience. We worked then on crystals, not on dipole sums but on ones like quadrupoles, which do converge. After his PhD he went back to their staff, and a few years later I got him back to a vacancy on our staff in London, where he stayed and is now a Reader. We’ve collaborated, off and on, ever since – and very often Edwin Power has been in the group as well.

Another very famous Australian at University College around that time was H S W Massey, whom you mentioned earlier. He was a Fellow of this Academy till he died.

I knew him quite well. He became Quain Professor of Physics, but when I first knew him he was Professor of Mathematics, running courses on scattering theory as he prepared to write either the second edition of his first book, or his second book. A number of us from Chemistry went over to hear his excellent lectures but as a kind of price for attending these lectures he inveigled us into working through the examples in his book, which were really quite hard going. He was quite a good cricketer. We used to have Physics vs Chemistry matches out at the College grounds, and he would turn out for Physics. Massey and Ingold formed a pretty formidable pair, and working together they could get finance and most of the things they wanted out of the College committee.

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International journeys

At about this time you established a number of international links. Travelling here, there and everywhere wasn’t all that easy in those early days, was it?

It was difficult. I had been to Europe, but the very first trip I made to the US, in the ’50s, was under the aegis of the Office of Naval Research. In those days it was easy to have contracts to do such things, and one of the perks was that you could get a free ride to the US on a military-type aircraft. John Pople, Stuart Walmsley, various others and I were going to the first meeting of the International Molecular Crystal Symposium, in Durham, North Carolina, and we were offered rides on the Military Air Transport Service of the US Army.

The first thing you had to do was to be made a member of the military, so we were all made Majors overnight: Major Pople and Major Craig and Major Somebody Else. We all went up to Mildenhall to get on board a converted Second World War bomber – very uncomfortable, with metal seats, and very noisy. As we were getting towards Newfoundland, there was word from the captain that he was having carburettor icing problems and would have to land at Harmon Field, which is a military air force base in either Iceland or Newfoundland. So we had to spend a very uncomfortable night in the other ranks' quarters there while the problem of the carburettors was being looked into. We got off next day but when we arrived at Newark, New Jersey, at night, there was nobody in attendance. (It was the military airfield, not the civilian one.) ‘Major John Pople’ got on the blower and made a fuss, and finally somebody came out, took us on board and helped us with the rest of the journey – but too late for the opening of the conference.

On these international journeys, such as that one to the United States, were you going to conferences or to visit specific people?

That was a specific conference, but we did other things as well. Pople, Walmsley and I hired a car and did a lot of visiting, in Canada as well as the US, and a number of collaborations grew out of such visits. For example, I worked with Bob Gordon, of Kingston, Ontario, on the spectra of highly dilute vapours, with some nice outcomes. A number of other students I met there or later but I can’t think of any particular research projects that came out of that. The contacts were always useful, of course.

Unfortunately, in the course of the crystals meeting I got mumps, one of the early signs of which is a very bad breath, halitosis. The first I knew of it was that I’d be sitting on a bench with people, talking science, and I would see them edging away a bit! By the time I got to Hamilton, Ontario, it was full-blown mumps, but fortunately an old University College pal, Ron Gillespie, who was there as Professor, and his wife took me in. It was something for them to do that, and otherwise I would’ve been in a bad way. Afterwards I made a few more trips in Canada and then came back.

You said you had been to Europe as well.

Yes. Some of the most interesting trips were to Eastern Europe. In 1958, when I was still at University College, the British Council sent me to Czechoslovakia and then to Russia for a month each – very instructive. In Russia it was bureaucratic madness in those years. To make even the slightest variation to arrangements that had been agreed beforehand was almost impossible. I wanted to change from train travel to air travel between Moscow and St Petersburg, or Leningrad as it then was. I started quite early: I spoke to my guide and I spoke to the guide’s boss, and then I spoke to the head of the department. I kept on speaking. Their standard response was always, ‘We will see what can be done.’ But the day came and went before any action. In the end nothing was done and I travelled by train, the Red Arrow, from Moscow to Leningrad. Czechoslovakia was much freer. You didn’t feel the same weight round you. I’m sure it’s changed in Russia now, but it was really a formidable undertaking in those days. It was a tremendous relief to me to get out to Finland. I felt, ‘Well, now I can breathe again.’

Did you meet Davydov during your Russian trip?

Yes, at the University of Moscow – and also in London. We had many contacts.

I believe you had an arduous journey by sea which had some amusing aspects to it.

This happened when my family and I were returning to London in 1956. Again we travelled by cargo steamer, this time the Imperial Star, of the Star Line. We left from Brisbane, travelling around the north of Australia through Torres Strait and across towards Aden. But when we were a day’s steaming from Aden the message came through that the Israeli war had broken out, so we did a 90 degree turn to port and went down to Cape Town. It had been a full month from one sight of land to the next, and the crew was pretty restive. There was some trouble in Cape Town and they came on board loaded with the local grog, there was a bit of a fight and one of them was knifed in the chest.

There were eight passengers on board, of whom my family accounted for five, with the ship’s doctor and his wife and a Lady Monckton. The ship’s doctor was fresh out of medical school and he hadn’t really much experience. When the captain said, ‘I’m sorry, doctor, but we’ve got a knifing, in the chest,’ he said, ‘I haven’t any idea about chests!’ The captain told him, ‘Well, you’re it. Get on with it.’ He did his best, the man duly recovered, and on we went. It was about eight weeks from Brisbane to our landing in Hull, and all that intervened.

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You have brought with you a primitive means of calculating. What is it?

It is called a Curta hand calculator, and it enables you to do simple arithmetic – you can multiply and divide. Supposing you want to multiply a number by another one, you put the first number down here in these little channels and it shows up like this. If you want to multiply that by 25, let’s say, you do two rounds, move it one position, and then five more. Then you read the result off and it’s never wrong.

I began, as probably others did, with the Fuller calculator, which was a form of slide rule wound on a cylinder so that you had about five feet of effective slide rule length to work on. They were quite good for their time.

I take it that neither of those was the sort of thing you were doing your large computations on at University College.

No, they were not any good for diagonalising matrices. The electromechanical ones we had in London were noisy and slow but were a good deal better than anything we’d had before. We had Brunsvigas but then we had the Marchant electromechanical calculator and extracting the roots of a six by six determinant was really a full day’s work. Ian Ross was very good at it, and I don’t think you could’ve beaten his record of about a day. Now, of course, we can do that in microseconds.

People had immense patience, didn’t they?

Oh yes. Anything beyond six by six I think I would have baulked at, though people tell me they’d done eight by eights. That must have been about a week’s work. And with those machines you get a partial result which you have to write down and re-enter, so if you’re doing it by hand there are mistakes.

You had to be very precise, too, in aligning the figures on slide rules accurately to get three or four figures off them. Your field must have profited enormously from the revolution in high-speed computing power since the days of a five-figure log book or a slide rule or other gadget. In your later days you even worked on supercomputers, didn’t you?

Yes. The factor of improvement in computing speed that I’ve seen in my working life is about 1012, so that it’s just a different world now. When I say this to experimenters, they say, ‘Well, it’s a funny thing, but that’s the same order of improvement that we have seen in the period of the minimum flash that we can use in photochemistry. It used to be, in the old days, about a hundredth of a second, and now it’s around a femtosecond.’ You just wouldn’t contemplate undertaking these structure calculations back then, and the world of ab initio calculations of small molecules was simply not within sight 20 years ago. Now people can get very precise results on sizeable molecules, just because computers are so powerful.

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Bringing Australians home to the ANU

You have made many oscillations between Australia and Britain and elsewhere, but in 1967 it was back to Australia, to the ANU. What was the background to that?

The first indication was a visit to London by Hugh Ennor (later Sir Hugh Ennor, Secretary to the Department of Science). He was then working in the ANU, and came to talk to Birch and to me and to Ron Nyholm in our various haunts in England. It wouldn’t have done for the College to have any inkling of what was going on at that stage, so we met outside the College, in an Express Dairy Cafe on Euston Road – one of those places where the early morning clerical assistants nip in for a quick cup. So we looked at one another across a pool of coffee left by other drinkers and he explained to me what the ANU had in mind, which was essentially that they wanted to create a centre of chemical research which was so good that it would attract back some of the cohort of young, able scientists from Australia who’d gone to the US or Britain. The ANU wanted somewhere excellent that these people could return to, somewhere very well equipped and all the rest of it. That caused my first spark of interest, and I think Nyholm and Birch reacted with similar interest. We made about three trips out to talk to Council and to Huxley, the Vice-Chancellor.

When the project began to take shape we got serious and we agreed to participate, and then the University agreed to plan the building. They sent an architect and an architect’s draughtsman to London, who set themselves up in a room the University had hired in Brown’s Hotel, Half Moon Street. It was all frightfully secret as we three ‘advisers’ to the project would troop down there, separately or together, to tell them what we thought was required for the various floors of Inorganic, Organic or Physical. They would build them into working drawings; we’d go again and confirm; and this went on. After a month or six weeks we had agreed working drawings.

But at the very last moment there was a hitch: a telephone call from Tom Owen, who was the building works supervisor, to say that funds had unfortunately run down a little bit and we’d have to change the module from 12 feet to 10. The module is the unit of building, the scale, so this was a shocking blow. But the architects took it nobly and we had no alternative but to say okay, we were still interested. And so the building was revamped at quite a late stage to accommodate that change of size.

But it’s a very fine building, isn’t it? Arthur Birch was very proud of how well it was done and how well it looks. It’s a relatively cheap form of construction, I believe.

Yes, the external building was very cheap, and in appearance it does show a good, strong vertical treatment. The secret of its success is that there are no internal walls. There are pillars, of course, but the internal accommodation can be juggled with great freedom, so a laboratory can be made bigger or smaller just by shifting partitions. We insisted on excellent servicing, with everything laid on – nitrogen gas and all the rest of it – and we were well looked after with equipment.

Did you not come out till it was complete?

No, although we were out at least once, maybe twice, in the course of construction. We had the great good fortune to have on site the man who became the lab manager, John Harper, who supervised construction or looked after it from the user’s point of view, and Rod Rickards, who looked after it from the scientist’s point of view. Rod had been recruited from Manchester, where he had been with Arthur Birch. The building is very well adapted to its purpose. We have no great revisions that with hindsight we’d like to have made – and of course the secret is to have no internal walls.

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Recognition, projects and influential roles

I want to turn now to your role in the Academy, David. Just after you’d returned to Australia to take up the appointment at the ANU, you were elected to the Royal Society. I wonder whether they were trying to entice you back to Britain once more.

I don’t think they would have thought of me as important as all that, Bob. No, I don’t think there would be any coupling between those possible events.

You were elected to this Academy one year later, and became Treasurer in 1985, for four years – that’s quite an onerous job – and then President from 1990 to 1994. The Academy was doing a number of things while you held each of those positions. What do you think are the highlights of that time?

Well, certainly my recollection of the Treasurer’s appointment was of dealing with the Becker Bequest, which was a major thing from the Academy’s point of view. Becker was a huge benefactor of the Academy and had already donated the Dome, and we knew that we were beneficiaries under the will even before my time as Treasurer. The will was contested for some time, however, and there were separate parts of the bequest – jewellery and so on. It all came to a head, as it were, in my time as Treasurer and we had to learn how to invest and how to exploit the talents of our Finance Committee, who greatly helped us. They included Ian Potter, the sharebroker – he was very influential not only in that capacity but also through the Potter Foundation and his contacts – and Meredith Ryan, secretary to AMP, and Sir John Wilson, of the paper manufacturers APM. He too was a very shrewd businessman. Also, Ros Greenwood, who came at that period, was a tremendous help with the investment side. That was my biggest task at that time.

The Australian Foundation for Science has gone from strength to strength, hasn’t it?

Yes. The Foundation was separate from the Becker estate. It had been in the mind of the previous President, David Curtis, but it took shape in my Presidency. In fact, that’s the major thing we were about. We made inquiries widely and we got professional help from the National Fund Raising Counsel of Australia for a funding campaign.

We had to do a lot of legwork trying to influence big companies to help us. Keith Boardman was very often with me when we did that. Our very first approach was to CRA, and by a stroke of the greatest good fortune John Ralph said yes and gave us $125,000. We could hardly believe that this was fundraising – this was munificence of a high order – but it never happened again. We did the rounds of many, many firms, but although they were all interested and many have since supported us by way of project finance, that has not been untied finance such as CRA gave us. That was marvellous.

We have had some successes, and in the course of that Presidency we had Primary Investigations getting under way and Environmental Science, both of which have been very successful. I really think the Foundation was what I was most interested in and concerned with, and it’s going very well.

Besides the behind-the-scenes interaction that there has always been between the Academy, through its senior officers, and government, you were also on the Prime Minister’s Science and Engineering Council and a member of the QEII Fellowship Scheme. When were you on the Executive of CSIRO?

That was from 1989 to ’95. That was a big task, one I enjoyed very much. I was involved in the health and safety problems, because one of the staff – at Fishermens Bend, I think – had died from exposure to some chemical or other and Barry Jones, the then Minister, insisted that there be a proper health and safety investigation by a committee. I was made chairman of that committee, and we had some very good people, outsiders, on it. We went to most of the CSIRO Divisions and came up with recommendations which were really quite severe, but I was pleased that the Executive adopted most of them and they’ve been put in place. When I came to finish my term on the Executive I had a nice letter from Barry Jones which said, ‘On your having now reached 65, I can no longer appoint you to the Executive – unless you can change your age or become a woman.’ So my term with the CSIRO ended.

Did you have any exciting times on the PMSEC?

It was a time when that Council was establishing itself as influential, although its influence has fluctuated since. Bob Hawke, who was the Prime Minister at that time, was almost always present at Council meetings for most of the day and he did take account of what people were offering by way of suggestions. The members were then a mix of industry and academic and university people, and you got a lot of very interesting opinions thrown up. There were subcommittees appointed, which reported back, and I do think it was influential.

And the QEII Fellowship Scheme has done a tremendous amount of good work.

Yes, that was very good. It was eventually subsumed into a government scheme, to my regret, but we did have excellent conditions to offer. The salary was good, the tenure was quite long, and we got very good people applying, many of whom have since gone on to important positions. That was very satisfying. When it became incorporated into a wider government scheme that had different levels, it kept the name QEII for the top level of it. You can still get a QEII Fellowship.

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Honours, a citation classic and a scientific retirement

For that work and for your eminence as a scientist generally, in 1985 you were made an Officer of the Order of Australia. Your distinctions include a DSc from the University of London, an honorary doctorate from the University of Sydney and, somewhat unusually, an honorary doctorate from Bologna. Tell us about that.

Well, I had had a long association with that university. There was a lot of to-ing and fro-ing and I had a number of their staff as my students or postdocs – Carlo Zauli was one in particular, a most able man. I had a lot to do with Bologna, one way and another, and I went to their 900th anniversary, celebrating their establishment in 1086. Also, there had been this early connection with Ingold and Mangini, who I think always had a soft spot for Ingold’s people. His department is very powerful. It’s called the Department of Industrial Chemistry, oddly enough, but a lot of its work is as fundamental as you could have, and there are some very good people there.

Mangini himself was a great figure in Italian science, which is run on rather unusual lines – professors are appointed not by their universities but by a Commission which sits in Rome, and for life. If you are just a young man and recommended to a professorship, you’re sent off to some lesser place, some smaller university, and then as you grow older and more wise you come up the line and finally you get to Bologna or Rome or somewhere like that. It’s a very interesting system, where the universities’ influence on those promotions is really very small and you’ve got to be a member of the Commission to have power. But they’re quite well funded – the equipment is there.

Your CV includes a long, impressive list of prizes, awards and visiting lectureships, but I won’t embarrass you by reading them all out. Your publication list includes a 1982 Current Contents article cited as a ‘citation classic’. What does that mean?

If a paper is quoted often enough in the Citation Index they treat that as a citation classic. They send you a very nice bit of paper and ask you to submit an account of how the work was done, which is rather good.

What was the paper upon which that was based, and why does it get cited so much?

It was the paper that I did together with Nyholm, Maccoll and Leslie Orgel, who’d been a pupil of Leslie Sutton in Oxford. It was to do with the overlap integrals between atoms using d orbitals in their binding. Overlap integrals you could do nowadays in a very short time, including programming, but at that time it was a lot of work and we had to make sure we got the same results in Oxford and London.

I think the paper was cited so often because it was the basis of an improved picture of bonding, with elements like sulphur, the heavier elements, in which not only the p orbitals and the s ones are used – as they are in oxygen and nitrogen, for example – but the d orbitals as well. And to get a picture of how important they are, you need some measure of their ability to overlap with the orbitals of adjacent atoms. You need to know how well the p orbital of oxygen overlaps with the s orbital of sulphur, for example. So we worked out all those tables which people used, and we gave our view of which compounds this sort of thing was going to be important in, both transition metal compounds and inorganic compounds of other kinds.

After your retirement, a number of years ago now, you were first of all a University Fellow at the ANU for a three-year term, weren’t you? You’ve continued as a Visiting Fellow in the Department of Chemistry, and you still write papers and generally carry on with your science interests.

Rather thinly spread papers, let’s put it that way! But I do keep an interest in electrodynamics, particularly, which I think is fascinating, and I’m very interested in the interaction of optically active materials, which underlie so much of life. You get a very good handle on that sort of thing using the methods that I now use in molecular quantum electrodynamics. So that really is the basis of my interest there.

What is your title at University College? Do you still visit there?

Yes. I am a Visiting Professor. I used to go back every year but now it’s every couple of years.

Well, that’s about where we will draw it to a close. Thank you very much, David, for a fascinating interview.

Thank you, Bob, for your good eliciting.

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