Optimizing efficiency of perturbative Monte Carlo method

We introduce error weighting functions into the perturbative Monte Carlo method for use with a hybrid ab initio quantum Ž . mechanicsrmolecular mechanics QMrMM potential. The perturbative Monte Carlo approach introduced earlier provides a means to reduce the number of full SCF calculations in simulations using a QMrMM potential by evoking perturbation theory to calculate energy changes due to displacements of an MM molecule. The use of weighting functions, introduced here, allows an optimal number of MM molecule displacements to occur between the performance of the full self-consistent field calculations. This will allow the ab initio QMrMM approach to be applied to systems that require more accurate treatment of the QM andror MM regions. Q 1998 John Wiley & Sons, Inc. J Comput Chem 19: 1632]1638, 1998