FINITE-ELEMENT INTERPOLATION FOR COMBINED CLASSICAL-QUANTUM MECHANICAL MOLECULAR-DYNAMICS SIMULATIONS

A method is presented to interpolate the potential energy function for a part of a system consisting of a few degrees of freedom, such as a molecule in solution. The method is based on a modified finite element (FE) interpolation scheme. The aim is to save computer time when expe nsive methods such as quantum-chemical calculations are used to determ ine the potential energy function. The expensive calculations are only carried out if the molecule explores new unknown regions of the confo rmation space. If the molecule resides in regions previously explored, a cheap interpolation is performed instead of an expensive calculatio n, using known neighboring points. We report the interpolation techniq ues for the energies and the forces of the molecule, the handling of t he FE mesh, and an application to a simple test example in molecular d ynamics (MD) simulations. Good performance of the method was obtained (especially for MD simulations with a preceding Monte Carlo mesh gener ation) without losing accuracy. (C) 1997 John Wiley & Sons, Inc.