The QUASI Project
QUASI (Quantum Simulation in Industry) is a collaborative research project to implement techniques for combined QM/MM (quantum mechanics/molecular mechanics) simulations on a variety of High Performance Computing (HPC) platforms, and to apply the techniques to industrial catalytic chemistry applications.
The project was coordinated by Daresbury and ran for 3 1/2 years, Jan 1998 to June 2001. Software developments were conducted in collaboration with the groups of Prof. Walter Thiel at the Max Planck Institute für Kohlenforschung, Mülheim, Germany, and Prof C.R.A. Catlow at the Royal Institution (London, UK). The demonstration and applications work has involved modelling teams from within three major European chemical companies; Norsk Hydro (Porsgrunn, Norway), BASF (Ludwigshafen, Germany) and ICI (Middlesborough, UK). For full partner contact details please see the project web page .
Software and Algorithm Development
The QUASI software environment is based on ChemShell, a Tcl-based computational chemistry environment which is described in full in another section of this report. The QUASI partners have extended ChemShell to support the requirements of the systems to be modelled and to make the software easier to use in an industrial setting These developments have included
QUASI is available for MPP computer systems, the MPP version allowing efficient operation of the DL_POLY, GAMESS-UK and GULP modules and the QM/MM models derived from them. In future versions this will incorporate MNDO also.
The Industrial applications sub-projects within the QUASI project (see below) have made extensive use of the Alpha-based beowulf system with QSNet interconnect (loki). The code is currently being ported to the Origin system (green) provide by the CSAR service at the University of Manchester for use by members of the Materials Consortium.
Industrial Applications Sub Projects
A major element of the QUASI project was a series of demonstration and application sub-projects that were conducted in collaboration with the industrial partners.
The QM/MM approach to zeolite modelling follows that used in previous studies , with a forcefield based on the CFF valence forcefield of Hill and Sauer . We have used the QM/MM model to characterise the structure of the ZSM-5 framework with a single Cu atom adsorbed at a number of sites (ring, interstitial etc). The energies and structures of a number of species occurring in the catalytic decomposition on NO2 and N2O at these sites have been characterised, including the transition state for the decomposition of adsorbed Cu-OONN into Cu-O and N2O. So far it appears that the intersitital sites, with just 2 Cu-O interactions are more catalytically active than the more heavily coordinated ring sites.
The basis of this sub-project was the solid-state embedding scheme incorporating QM calculations performed using GAMESS-UK in an environment modelled using shell model forcefields using the GULP code. The project has characterised the energies of a large number of species implicated in the Cu/ZnO catalysed methanol synthesis process, using an oxygen terminated (000-1) surface of Zincite. The energetics of the involvement of vacant oxygen interstitial sites has also been explored. In a number of cases vibrational frequencies have been characterised and shown to be in good agreement with experiment. A series of calculations on adsorbed Cu clusters of varying sizes have been performed and these will form the basis of further studies on the Cu-catalysed chemistry [2,3].
 Samuel A. French, S.T. Bromley, A.A. Sokol, C.R.A. Catlow, J. Kendrick, S. Rogers, P. Sherwood. Presented at the 2001 MRS Spring Meeting and due to be published in the proceedings.
 S.T. Bromley, A.A. Sokol, C.R.A. Catlow, S. Rogers, F. King, and P. Sherwood.: Angewandte Chemie, In press
 S.R. Billeter, A.J. Turner and W. Thiel, Phys. Chem. Chem. Phys 2: (2000) 2177
 A.H. de Vries, P. Sherwood, S.J. Collins, A.M. Rigby, M. Rigutto and G.J. Kramer, J. Phys. Chem., 103 (1999) 6133.
 C. Lennartz, A Schäfer, F. Terstegem, W. Thiel. J. Phys. Chem. A, Submitted.
 S.R. Billeter, C.F.W. Hanser, T.Z. Mordasini , et al. Phys Chem Chem Phys 3 (2001) 688-695.