Preface

Anthony Stone's 70th birthday provides a welcome opportunity to pay tribute to him as an outstanding scientist, universally appreciated for his rigour, availability and modesty. His distinguished contributions to theoretical chemistry have formed the basis for a growing range of computational chemistry applications. Many of his seminal contributions have been published in Molecular Physics, and are being cited decades later. Hence it seemed fitting to have a Special Issue of Molecular Physics in his honour. A call for papers has resulted in a substantial issue, containing 24 papers from past collaborators and students who are leading authorities in their fields, ranging from further developments in the theory through to diverse applications. Several people would have liked to pay tribute to Anthony in this way, but are now working in fields too far from the scope of this journal: Anthony's Molecular Physics papers are being cited in journals of pharmaceutical science, mineralogy, molecular biology and physics. As guest editor, I am also aware of many people who contributed to this Special Issue as referees, continuing to maintain Anthony's scholarly standards and ability to provide helpful constructive criticism.

Anthony Stone was an undergraduate at Cambridge, followed by a PhD there with Christopher Longuet-Higgins on g-tensors. He did a post-doc at Florida State University with Michael Kasha, before being appointed as a Senior Assistant in Research in Chemistry at Cambridge in 1964. He has been based at Cambridge ever since, progressing to holding a personal chair in Theoretical Chemistry prior to his retirement in 2006. His research has evolved from the application of symmetry to a wide range of problems, from the theory of intermolecular forces to chemical bonding in boron hydrides, transition metal complexes and non-rigid molecular structures. His papers have been marked by clarity of thought and expression, and careful attention to detail, that have both enabled people to take up the methods, and stood the test of time. This has also been made possible by his generosity of spirit in developing and maintaining the computer programs that incorporate his theories, extending them with students and collaborators. This includes fixing the rare bugs, and showing considerable helpfulness and patience with those who haven’t really understood the documentation. The programs range from a Wigner coefficient calculator, through to ORIENT, which allows anisotropic atom-atom potentials to be used in modelling a huge range of complexes and surfaces. To use just one contribution as an example, Distributed Multipole Analysis is a widely used methodology which only Anthony himself felt the need to revise after 25 years (to allow for better quality wavefunctions), and which he has made available to a range of users by writing and maintaining interfaces to other ab initio packages.

Anthony is inspirational leader as well as a great collaborator, and has helped tackle many problems by extending the theory and programs. Anthony's advice and help continues to be highly appreciated by experimentalists in the Cambridge Chemistry Department. He has been involved in many external collaborations whilst based in Cambridge, where in addition to his research and teaching, he has played a major role at Emmanuel College where he has been a fellow since 1964. This has included not only being a Tutor and Director of Studies in Natural Sciences for decades, but also being Admissions Tutor, Steward and Vice Master for several years, which included overseeing the election of a new Master. He has been married to Sybil since 1967, whom he met through their joint love of gliding. Other shared leisure interests have been more down to earth, and include hill walking and English, American and Scottish country dancing. Anthony and Sybil have jointly raised three children, and many contributors will remember hospitality at their family home in Fulborne, which is now enjoyed by their four grandchildren. Despite the ties of family and Sybil's medical practice, Anthony's collaborative work did lead to some sabbatical visits, notably to Bill Meath at the University of Western Ontario and George Ewing in Bloomington, Indiana. Anthony's book, “The Theory of Intermolecular Forces” arose from the lectures Anthony gave as Visiting Professor at the Université de Franche Comté in Besançon in 1993. Many of the thousands of copies of this monograph are heavily used by research groups around the world.

Many of Anthony's students, postdocs and collaborators are very grateful to him for his support in their self-development as scientists and individuals, as was evident from the warm tributes paid at his retirement celebrations, from those who had left science as well as those who have continued. I am particularly grateful, for thirty years of learning, friendship and support from Anthony. Our collaboration in applying Anthony's methods for deriving accurate model intermolecular potentials for organic molecules is at an exciting stage, with the once ridiculously ambitious idea of deriving such potentials purely from theory becoming a reality. This was shown by the success of such a potential for C₆Br₂ClFH₂ in the recent international blind test of crystal structure prediction 1, as one of the first applications of the program CamCASP which Anthony and Alston Misquitta are currently developing. Alston's contribution to this Special Issue summarises Anthony's support nicely: his advice and scientific guidance were so important that it needed recognition by coauthorship, yet working with him is “sheer fun”. The level of activity in the many fields that have benefited so much from Anthony's input and the increasing range of applications are apparent from this Special Issue of Molecular Physics. A second edition of “The Theory of Intermolecular Forces” would also be timely. Thus, whilst we wish Anthony a very happy 70th birthday, a long and happy “retirement”, we also need him to continue as an active founding father of the field.