Algorithms, developments and applications in molecular modelling: the GAMESS-UK Ab Initio code

Focusing on molecular electronic structure, an outline is presented of the range of methods commonly used in computational chemistry, with consideration given to the accuracy, limitations and performance costs of the HF, DFT, MP2 and CCSD methods in understanding neutron-scattering related phenomena. Using GAMESS-UK as an example of a large electronic structure package, we illustrate the capabilities of these methods in computing the geometrical structures of transition metal complexes. These studies both reinforce the value of DFT, and reveal an overall inconsistency in the MP2-based predictions. Finally, emphasis is given to the cost effectiveness and applicability of the spectrum of hardware available to the computational chemist, from the single-user PC to massively parallel processors (MPP). We illustrate the potential of the latter platforms in enhancing the level of desk-top simulations by two-orders of magnitude, and demonstrate the potential of parallel PC-based Beowulf Systems.