Reliable large scale simulations of quantum mechanical molecular dynamics to determine the properties of solid state and molecular systems from first principles are becoming increasingly important as new and emerging technologies make demands for engineering at the atomic and molecular level. The principal goal is the parameter-free determination of the energy and electronic charge distribution in these materials. From this, it is possible to determine bond character, equilibrium geometry, energy differences between various conformations or phases, vibrational properties, dipole moments and polarisabilities. Using accurate quantum mechanical simulations, reliable information on these properties can be calculated, which can be extremely difficult to obtain by experiment.
To achieve the above aims in molecular and solid state systems it is necessary to address the formidable task of solving the associated many body Schroedinger equation. In order to do this we use a number of techniques. For example, one very accurate approach which we use is large scale first principles electronic structure calculations based on density functional theory. These can obviate many of the drawbacks of standard methods of quantum chemistry, and open new opportunities in the field of computer simulation of molecular materials.
Present research interests in first principles techniques include development of exchange and correlation functionals for use in density functional theory which can accurately describe both ground state and excited state properties.
The areas of interest using first principles methods to model materials span a wide range of different materials, including liquid crystals, molecular fluids, molecular crystals and semiconducting systems, and involve collaborations with the Chemistry Department in Durham, and groups at Edinburgh and Cambridge. In the area of semiconductors, we have a particular interest in GaN and other nitride-based materials.