Ab initio diffusion Monte Carlo calculations of the quantum behavior of CH5+ in full dimensionality
aDepartment of Chemistry, The Ohio State University, Columbus, Ohio, 43210
bDepartment of Chemistry and Cherry L. Emerson Center for Scientific Computation, Emory University, Atlanta, GA 30322
cAlso: Department of Mathematics and Computer Science, Emory University, Atlanta, Georgia, 30322
dPermanent Address: Department of Chemistry, University of Alberta, Edmonton, AB, T6G 2G2, Canada
Abstract
We report an ab initio calculation of the potential surface, quantum structures, and zero-point energies of CH5+ and CH2D3+ in full dimensionality. This potential energy surface is a very precise fit to 20633 ab initio energies and an even larger data set of potential gradients, obtained at the MP2/cc-pVTZ level of theory/basis. The potential, which exactly obeys the permutational symmetry of the five hydrogen atoms, is used in Diffusion Monte Carlo (DMC) calculations of the fully anharmonic zero-point energies and ground state wave functions of CH5+ and CH2D3+. Bond length distributions are obtained from the DMC ground state and are compared to those resulting from classical molecular dynamics simulations, which are performed at the quantum zero-point energy for roughly 300 picoseconds.
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Last updated June 6, 2004.