Our colleague Weihong Zheng died in January 2007 of cancer, at the tragically early age of 42. He was a Senior Research Associate working with Jaan Oitmaa, Chris Hamer and Oleg Sushkov on the theory of strongly interacting lattice models in condensed matter physics. His loss is a sad blow to our group, as well as to his family and friends.

Zheng studied at Zhongshan University in Guangdong, China, where he obtained his PhD in 1989. His thesis work was done with Professor Guo in the field of lattice gauge theory. He was a brilliant student, and after a brief Visiting Fellowship at the Institute of Physics in Beijing, he was appointed as a Lecturer at Zhongshan. Shortly afterwards, he made enquiries about working with us at UNSW. At the time, no position was available, but in 1991 an opening occurred and he was able to join us as a Research Associate.

He remained with the group in later years, funded by a succession of ARC grants, and quickly became the indispensable engine-room of our activities. He had enormous talent as a computational physicist, and could produce reliable, accurate results with amazing speed. His main work concerned perturbation series expansions for quantum lattice models. His original interest was in lattice gauge models in particle physics, but the focus rapidly shifted to spin models of magnetic materials, and electron models of conductors, which have been the major interest of the group in recent years.

Zheng was a tireless worker, and was always happy to help others with lesser computing skills. He developed a huge, multipurpose computer code for series calculations, and published over 100 papers in first-class scientific journals. In the last few years, his talents were becoming increasingly recognized in the outside world, and he began developing valuable collaborations with Professor Ross McKenzie and his group in Queensland, Professor Rajiv Singh at UC Davis, and experimentalists at Oak Ridge and Rutherford Appleton laboratories. Our group had established a world-leading reputation in series expansion methods, capped off by the publication of a book by Oitmaa, Hamer and Zheng on ‘Series Expansion Methods for Strongly Interacting Lattice Models’ by Cambridge University Press in 2006. It is a tragedy that his career should be cut short just when it was beginning to flourish so well.

Zheng was a delight to work with, always cheerful, always helpful, always positive in his attitude, a loyal friend and colleague. He kept working as best he could right up until the last few weeks. The loss of his expertise will leave an enormous gap in the group’s activities and capabilities.

In the mid-90s Zheng married Wenxiang Zhou, who came out from China to join him in Sydney. They had two young daughters, Alisa and Jessica, who are only now reaching secondary school age. Zheng took great delight in his two small girls, and spent much time ferrying them to and from school and to other places. We extend our heartfelt sympathy to his family on their cruel loss.

Chris Hamer and Jaan Oitmaa