Historical profile The lost Boys of quantum chemistry Dermot Martin profiles Frank Boys, an unsung hero of theoretical chemistry When the English quantum chemist pharmaceuticals, electronics and exploration, the interpretation of Sir John Pople won a Nobel prize in In short nanotechnology. We create proteins biostructures and the mapping of chemistry in 1998, it was the ultimate Early computational to target viruses, and marvel at the genomes, but it has never gained recognition of a lifetime dedicated chemistry laid the world of bioinformatics and the the same kudos. It is almost as if the to understanding the mathematical foundations for making quest for newer tools to smooth our scientists carrying out this work are basis of chemical bonding. ‘designer molecules’ way in the digital world. What we invisible. By this time mathematically for drug discovery and tend to forget is that these advances There remains a huge void in the minded chemists such as Pople had nanoscience all have their foundations in public perception of the tools which been chipping away for more than The people carrying computational chemistry. have enabled us to grasp the nature of half a century on calculations which out this work tended This branch of chemistry has atomic structure – molecular orbital brought us all closer to ‘chemical to inhabit an invisible evolved in parallel with space theory, quantum mechanics and truth’. And four other scientists world, rarely receiving refined mathematical methods. had been awarded Nobel prizes for recognition for their input Pople was a pivotal figure in their theoretical chemistry work: One such chemist was creating the first generation of Linus Pauling, Robert Mulliken, Frank Boys, who made software capable of performing rapid Chandrasekhara Venkata (CV) important contributions calculations to explain the structure Raman and Gerhard Herzberg. to quantum chemistry of simple diatomic molecules. He Aside from these five men, many and our understanding of laid the path to creation of Gaussian of the closely knit community of the chemical bond software, which became the bedrock quantum scientists have remained of programming languages used by unknown to the wider scientific computational chemists. But the work population – even though their of others also deserved recognition. complex, esoteric work has become One such chemist was Samuel an indispensable tool spanning areas Francis (Frank) Boys – the first of analytical and synthetic chemistry. person to begin coaxing the embryonic computers of his day into Behind the scenes creating an accurate picture of the Today we talk almost glibly about nature of the chemical bond. ‘designer molecules’ for use in Frank Boys (1911–1972) It was Boys who established a LTD COOPER C A 56 | Chemistry World | August 2010 www.chemistryworld.org theorem to prove that a wavefunction work on his PhD. Here he became for a molecular bond could be found adept at quantum mechanical with accuracy by superimposing a calculations, under the supervision sufficient number of configurations. of the physical chemist Thomas He demonstrated his theory by Martin Lowry. cracking the calculated structure On Lowry’s death, Boys was of tritium (3H) without the aid of a transferred to work with John computer. In doing so he realised that Lennard-Jones. ‘LJ’ was part of one alone. Chemists found him too to calculate more complex structures of Europe’s most advanced groups mathematical and not willing to stoop computers would be essential tools, of theoretical chemists who had to answer their problems.’ and he was determined to fully their own way of thinking. The team By 1938, Boys had his first academic embrace them. included luminaries such as Charles appointment which took him away Coulson and William George Penney, from any isolation he might have felt Up close and personal who were all thoroughly focused on in Cambridge to Queen’s University So who was Frank Boys? Born in 1911, work on chemical bond order and Belfast. There he became an assistant colleagues knew him as a modest valence bond theory. For Boys, the lecturer in mathematical physics Yorkshire man educated at Pudsey new working arrangement was not under Harrie Massey, the man Grammar School who went on to too successful. credited with introducing Francis graduate in chemistry from Imperial George Hall, emeritus professor Crick to the x-ray crystallographer College London in 1932. In his first of mathematics at the University of Maurice Wilkins. year at Imperial he attended maths Nottingham, who worked with Boys With the outbreak of the second degree courses to acquire a working recalls: ‘Frank must have been an ‘Boys was the world war, the UK government called knowledge of quantum theory, but outsider even then because his own first person to on Boys to move to the Ministry of his first research paper was on the interests were so far removed from Supply in Woolwich bringing him unrelated topic optical rotatory their own and his entry to the group coax computers back into the orbit of Lennard- power (published in 1934). was so induced. into helping Jones. His war work was centred on His academic talents were spotted ‘He fought for the rigorous explosives, particularly the study of early and he moved to the University approach to chemistry when it was understand munitions propellant during the of Cambridge in 1935 to continue his against the grain. He often seemed chemical bonds’ acceleration phase of the shell along www.chemistryworld.org Chemistry World | August 2010 | 57 Historical profile the gun barrel. Later he switched the theoretical chemistry team at Boys (centre) and Pople such as Edsac (electronic delay to the study of rocket fuels, both Cambridge taking with him two (second from left) storage automatic calculator) for theoretically and experimentally. female assistants whose sole job was outside the Cambridge encryption and code breaking. It Hall describes Boys as a shy to turn out integrals hour after hour department of theoretical was famous for calculating prime individual with a quirky sense using electronic calculators. Their chemistry in 1954 numbers – breaking the world of humour. During his time at work meant he was able to produce record in 1951 with the first 79-digit the Ministry of Supply his group analytical wavefunctions for some prime number. Later, when hooked refurbished a couch in the common simple atoms. His method was to up to a cathode ray tube it was able room with springs made from build up the calculations based to play a version of the game noughts the explosive cordite. Important on a selected number of possible and crosses. (Some computer visitors were invited to sit on the configurations of the molecule. historians claim this was the world’s couch before being told what they Boys adapted the method in a first video game.) were sitting on. general way and recognised that it These early computers would could be extended to even greater provide the impetus theoreticians After the war accuracy, but the calculations were needed to overcome the painstaking When the second world war expensive in terms of manpower and time-consuming manual ended, Boys took up an ICI (or in this case female power) and calculations needed to interpret fellowship back at Imperial extremely slow. Fortunately times bond parameters of simple atoms College London. His focus was were changing. and molecules. Boys became expert on producing wavefunctions that at optimising many operations on were accurate enough to predict The first computers the machine and his students soon important molecular quantities. The war years had been a driving became skilled in producing results This was the ultimate aim for force in developing early computers against near impossible odds. computational chemists – to perfect Boys was by now being relentlessly the mathematics needed to precisely drawn into the embryonic world predict physical properties, and to of computer programming. He apply the technique to ever more attempted to design a computer complex molecules. language driven by his awareness of Boys’s determination and total how these fledgling machines could confidence in quantum mechanics be used to take over the burden of meant he sought understanding manual calculation. of the transitory chemical species Before the University of that were beyond the reach of Cambridge upgraded to the second contemporary theory. Radicals, version of the Edsac, Boys realised he ions and unstable molecular needed to learn to program this new fragments were his target. He saw machine in advance so he could fully that if quantum mechanics could exploit its power and speed before be applied to predict behaviour and rivals for the machine’s time came reaction pathways, it would feed knocking on the computer room door. directly into any theory of reactions John Pople won a Nobel In those days every calculation and reaction rates. In this he was far prize for developing Boys and his team carried out had to ahead of his time in his thinking. computational methods be checked. This meant running the In 1949, Boys was back with for quantum chemistry entire calculation at a different time 58 | Chemistry World | August 2010 www.chemistryworld.org with no cross connection. It was the only way to confirm the accuracy. As Pople himself acknowledged years later: ‘I was late in recognising the role that computers would play in the field – I should not have been, for Frank Boys was continually urging the use of early machines back in Cambridge days. ‘However, by 1964, it was clear that the development of an efficient computer code was one of the major tasks facing a practical theoretician and I learned the trade with enthusiasm.’ Boys always felt that his approach to quantum chemistry could be extended to other areas of science. His first work was on the use of Gaussian-type statistical functions in closed systems – ie systems when, for statistical purposes in the calculation of molecular structure, it is assumed that no ‘external event’ comes in to play.