Modeling of high-order many-mode terms in the expansion of multidimensional potential energy surfaces: application to vibrational spectra.
High-order many-mode terms in the expansion of multidimensional potential energy surfaces were modeled by a fully automated molecule-specific fitting of parameters within semiempirical molecular orbital theory to low-order grid representations of high-level ab initio potentials. Analytical derivatives of the total energy with respect to the fitting parameters in combination with global and local optimization procedures allow for an efficient and accurate estimation of such terms. The accuracy of this approach was tested on the basis of vibrational SCF and configuration interaction calculations for the fundamental modes of a set of test molecules. Deviations with respect to reference calculations were found to be very small. Speedups in computation time by about three orders of magnitude relative to conventional calculations were achieved.
Rauhut
Guntram
G
Institut für Theoretische Chemie, Universität Stuttgart, Pfaffenwaldring 55, 70569 Stuttgart, Germany. rauhut@theochem.uni-stuttgart.de
Hartke
Bernd
B