In your life, you are fortunate indeed to be able to count a close friend as someone who has been your teacher and mentor; Ian Snook was such a friend. He was a talented and internationally recognized scientist, lecturer and research advisor; it was however, Ian’s generosity, humour and above all his humility that those of us privileged to know him most admired.
In every sense, Ian was a lateral and innovative thinker. He had considerable and adaptable skills in pure and applied mathematics, which he employed often and with great success in both developing computational methods and condensed matter theory. One only need read his monograph on the application of the Langevin and Generalised Langevin equations to the dynamics of atomic and complex fluids to recognise his mathematical prowess. His skill in recognizing geometrical patterns and resolving them through innovative mathematical methods enabled him to tackle many difficult problems in the area of colloid physics (in the early years) through to nanoscience (more recently).
We will not attempt here to describe in detail Ian’s life but will refer the reader to a website dedicated to him iansnook.com
2. Our perspective on Ian’s scientific contributions
Ian’s early scientific research began in the area of theoretical chemistry, where he developed intermolecular potentials for use in quantum mechanical simulations to enable the study of weakly interacting systems. His PhD thesis ‘On the determination of intermolecular potentials,’ was undertaken at the University of Tasmania. In 1971, he moved with his supervisor, Prof. Tom Spurling, to complete his thesis at CSIRO’s Firsherman’s Bend laboratory. Around this time, while attending his first international conference in Sydney, he met Prof. John A. Barker (a former head of the lab), who Ian described as having ‘a profound effect on the direction of my PhD and also on my subsequent career’ (see  below in the List of Ian’s Published Works). It was John’s seminal work on intermolecular forces and statistical mechanics of the liquid state that set the direction of much of Ian’s future research.
After his PhD, Ian published papers on potentials for He2 and He3 derived from quantum mechanical methods and semi-empirical potentials for CH4, CF4 and SF6. At this time, he published a single author article titled ‘Alternative derivation of Goddards Oii operator’ (see  below in the List of Ian’s Published Works). After these first few papers Ian began his studies in earnest in the area of condensed matter physics. This commenced with his work on the He4 liquid ground state with colleague and friend Prof. Bob Watts, who later became BHP’s Chief Scientist. It was Bob’s use of machine simulations methods, however, in work that he had been undertaking with John Barker that inspired Ian’s further interest in developing and using computational simulations.
After a short postdoc at the Australian National University (ANU) in Canberra (1971–1973) Ian returned to Melbourne where he was appointed to an Academic Lectureship in the Department of Applied Physics at RMIT University, where he joined his friend and colleague Prof. Bill van Megen whom he’d met at the ANU. The pair then set about establishing what can only be described as a prolific research partnership producing 53 papers over a 16 year period (1975–1991). These papers, together with two more recent articles, can be found in the list of Ian’s publications below. In 1994, Ian was promoted to Professor of Condensed Matter Physics, a position in which he remained until his death in 2013.
The deep insight that the pair gained about colloidal phenomena, by combining computational simulations with dynamic light scattering experiments has had a lasting influence in the field. Several of their studies are now given as examples in textbooks on computer simulations (see for example Refs. [1, 2]) and soft condensed matter physics (for example Ref. ).
This work, together with many further studies in the field of stochastic methods led to Ian’s monograph on ‘Langevin and Generalised Langevin Approach to the Dynamics of Atomic, Polymeric and Colloidal Systems’ in 2006 (see  below in the List of Ian’s Published Works). This book gives detailed technical descriptions of work that Ian did with many of his colleagues and students.
It was Ian’s interaction with these colleagues, students and postdoctoral fellows that provided long lasting memories for many of us who were at RMIT. In particular, it was his influence at the undergraduate level that attracted many students into postgraduate programs and later postdoctoral fellows that helped to grow the condensed matter group. Many of his students and researchers have gone on to have very successful careers in related scientific fields, notably Dr Amanda Barnard who received the 2014 Foresight Institute Feynman Prize – Theory, for her research focused on diamond nanoparticles. Many of Ian’s past students and colleagues are contributing articles for this special issue. With Ian at the helm the computational physics and condensed matter theory group was then built up to include current Professors, including Prof. Peter Daivis, Prof. Salvy Russo and Prof. Irene Yarovsky. Ian also had a great influence on other Professors in Applied Physics, such as Prof. Gary Bryant and Prof. Dougal McCulloch.
Over many years at RMIT, Ian also had numerous external collaborators in Australia and internationally, who appear as co-authors on many of his publications listed below. These connections led to many new outstanding discoveries.
Undoubtedly Ian’s international reputation (together with his amiable character and infectious humour) provided him with many visiting scientist opportunities overseas, including early visits to: Drs John Barker, Doug Henderson and Farid Abraham (IBM laboratories, San Jose), including a short postdoc position at MIT’s Ceramics Processing Research Laboratories; Prof. David Cannell (University of California, Santa Barbara); the late John Hayter (Solid State Physics Division, Oak Ridge National Laboratories, Tennessee); Prof. John Perram (Mathematics Institute, Odense University); Prof. Ruth Linden Bell (Atomic Simulation Group at Queens University, Belfast); Prof. Richard Needs and Dr Mike Towler (Cambridge University); and several recent visits to Professors Kurt Binder, Thomas Palberg and Tanja Schilling (Institute of Physics, Johannes Gutenberg University, Mainz, Germany).
These strong connections have led to a large body of work resulting in more than 240 journal articles, book chapters, review articles and his monograph. The full list of Ian’s scientific publications is included at the end of this article.
3. Ian’s place in the scientific computing community of Australia
For his PhD thesis Ian developed computer codes (written in FORTRAN, which was his language of choice) and for aficionados performed machine simulations on the standard scientific computing work horses of the time: a 24-bit word size Model CDC 3200 Control Data Corporation computer, ca. 1964 and an Elliot Brother’s Model 503 Mark II, ca. 1963. Some of the punch cards from these machines were proudly shown to many of his students. His exposure to these computing machines gave Ian an early insight into the capacity of in silico experiments to make important scientific discoveries. From then on, Ian was instrumental not only in developing RMIT University’s scientific computing capability, but that of Australia as a whole. It is no surprise that the continuous funding from the Australian Research Council grants awarded to Ian as Chief Investigator recognised his ability to solve important science problems using large-scale supercomputers.
He was a member of the board of the National Computational Infrastructure (NCI) facility, formerly known as the Australian Partnership for Advanced Computing (APAC). He was a committee member of the NCI/APAC Merit Allocation Scheme for which he was an assessor of many supercomputing research grants. He was also instrumental in developing the Victorian scientific computing facilities which became known as the Victorian Partnership for Advance Computing which is now part of the V3 Alliance. Overall, Ian significantly raised the value and standing of computational simulations in Australia.
4. Personal reflections
Rob Rees: To really know a person, often you must see them through another’s eyes. During my PhD I was struggling with a problem of a difference in results gained from Grand Canonical Monte Carlo vs. Molecular Dynamics simulations of Lennard-Jones particles adsorbed in cylindrical carbon-like nanopores. As a result, Ian consulted his close friend Ed Smith, who was at the time Professor of Mathematics at La Trobe University. Ed then set about masterfully guiding me through derivations of hypergeometric series solutions of cylindrical potentials, which require analytically continuous functions and which after implementation in simulation codes, resolved the problem (see  below in List of Ian’s Published Works). It was, however, in numerous cherished conversations that I had with Ed on the balcony outside his office at La Trobe Uni (on ‘Ed’s Smoke Break’), where I learned of his deep admiration and respect for his close friend Ian Snook. He spoke of their early interactions at the ANU, and their work with Bill van Megen and others at RMIT and beyond (for details, see  below in the List of Ian’s Published Works, an Editorial dedicated to Ed). Sadly Ed passed away on the 27 July 2009 but the level of esteem which they held for each other and for John Barker who influenced both their scientific careers, was obvious.
Ian was a well-rounded personality. His intellect and energy enabled him a broad range of interests. Areas like, for example, Celtic and Nordic mythology and classic literature where some of his favourite topics. As an avid speed-reader he could consume substantial texts with ease and with great recollection of detail. His knowledge of the fine arts and music was extensive and covered many genres and indeed he had quite a prolific music collection and knowledge of it. No doubt one of his greatest musical influences was his mother, Joan, who was his sole parent as Ian lost his father at the tender age of one. Joan had a tremendous natural musical ability despite having no formal training and played many instruments. Ian’s quirky sense of humour no doubt came from a love of the works of his contemporary British and American comedians, though his hybrid use of Australian ironical humour with Cockney rhyming slang was often lost on some.
To maintain a balance away from these more academic pursuits, Ian was a great sportsman, playing representative tennis and cricket for his school, university and during his postdoctoral years.
In later years his physicality extended into the development of the beautiful garden at his home in Vermont, Melbourne, which he shared with his wife of 43 years Marie Snook and their three children, Stuart, Graeme and Tamara. Ian and Marie were no strangers to tragedy as Stuart, their eldest child, died in October 2004. Today Ian is survived by Marie, their son Graeme and his wife Nina and their daughter Tamara and her husband Simon and children, Ian’s beloved grandchildren, Søren and Matisse.
It was to Ian and Marie’s home that many of us as his students, postdocs, friends and visiting international colleagues were welcomed into ‘The Snook Family’. With wonderful food and wine, we celebrated life in happy conversation, nurtured by Ian’s generosity, inclusiveness and his genuine love for the people with whom he surrounded himself. This is how I will always remember my dear friend, teacher and mentor, Ian Keith Snook.
Michelle Spencer: Ian was a great influence in my academic career. I first met him when I joined Prof. Irene Yarovsky’s group at RMIT University as a postdoctoral fellow in 2001, where we worked on modelling iron surfaces and interfaces with density functional theory. During this time I recall with great fondness the scientific discussions we had, as well as the Friday afternoons spent with the condensed matter theory group at the ‘round table’ for drinks, or more commonly known as ‘complex fluids meetings’.
In 2009 I commenced a new collaboration with Ian and Dr Tetsuya Morishita (who was visiting Ian from Japan’s AIST) investigating the two-dimensional nanomaterial silicene. Ian enjoyed coming up with what he called ‘crazy ideas’ for new things we could try modelling related to silicene, which reflected Ian’s love for learning and his enthusiasm for our work. This collaboration with Tetsuya has continued fruitfully to this day.
I fondly remember a number of occasions when I was invited to Ian and Marie’s place (a.k.a. ‘Maison Snook’) where both Ian and Marie were very generous and kind hosts. I also fondly remember our occasional email correspondences in French when Ian was visiting his collaborators in Europe. We managed to communicate quite well, even if at times our grammar was far from perfect!
Ian was always a very accepting person and showed great respect for me and my scientific ideas, and was highly supportive and encouraging. I especially valued his mentorship and support. Overall, Ian had a kind and friendly nature and a passion for learning and discovery that was infectious. I miss him greatly.