Multiple Cluster Model (MCM) for Surface Reaction Systems

摘要

Multiple cluster model (MCM) for investigating surface reactions is formulated. In this model the reaction center, where electron correlation effects often play a key role, is described by an accurate high-level approximation, and bulk effects such as the lattice distortion energy are evaluated using a simple low-level approximation. Therefore, the MCM can properly simulate the potential energy hypersurface of the surface reaction system with a feasible computational cost. since there exist no fixed atom in the MCM, we can rigorously characterize the stationary point (the minimum energy point or the transition state) on the potential energy hypersurface by vibrational frequency analysis. The MCM can be applied not only to surface systems, but also to various large systems. A detailed comparison of the MCM with the integrated molecular orbital + molecular mechanics (IMOMM), the integrated molecular orbital + molecular orbital (IMOMO), and ONIOM developed by Morokuma and co-workers is also presented.