## James Spencer

PhD student October 2005–March 2009.

I am now the Computational Science Support Specialist in the Thomas Young Centre and the Condensed Matter Theory Group at Imperial College.

### Research

I am interested in electronic correlation in periodic systems. Work over the last few years in the Alavi group has focussed on developing an electronic structure theory for molecules based upon the resummation of path integrals in Slater Determinant space and I am working on extending and applying this approach to periodic systems. Periodic systems are a very challenging problem for the electronic structure community. I have spent some time looking at issues such as the use of symmetry (and in particular non-symmorphic space groups) and finite size effects. Our work on the latter resulted in a new, efficient scheme for treating the exchange interaction in extended systems using a plane wave basis (PRB, **77**, 193110 (2008)). I gave a talk on this work at the Royal Society of Chemistry Theoretical Chemistry Group's
Graduate Student meeting in 2008 (slides).

The dispersive interaction between extended systems is a fascinating problem and is much stronger than one might expect from the atomic case. I am currently examining this using some simple model systems which capture the correct physics yet are computational much cheaper than modelling real materials. Using model systems allow us to explore finite-size effects in ways that are not otherwise possible. It is also very fun!

Science must be reproducible, and to this end I wrote a package which compiles and tests our programs to ensure our results are consistent over time. Much of my time is spent writing programs to explore these problems. As such, I have become interested in how we can better use computers to aid us in doing research. I like open source software, version control (git is my current favourite) and python.