MOLECULAR-POTENTIAL ENERGY SURFACES BY INTERPOLATION IN CARTESIAN COORDINATES

We present a new method for expressing a molecular potential energy su rface (PES) as an interpolation of local Taylor expansions. By using o nly Cartesian coordinates for the atomic positions, this method avoids redundancy problems associated with the use of internal coordinates. The correct translation, rotation, inversion, and permutation invarian ce are incorporated in the PES via the interpolation method itself. Th e method is most readily employed for bound molecules or clusters and is demonstrated by application to the vibrational motion of acetylene. (C) 1998 American Institute of Physics.