Random walk based approach applied to the H8 model: Comparison with coupled cluster levels of theory

PHYS 447

Shih-I Lu, shih_i_lu@hotmail.com, Department of Chemistry, Soochow University, 70 Lin-Shih Road, Taipei City, Taiwan
A random walk based approach implemented with the Ornstein-Uhlenbeck diffusion quantum Monte Carlo (OUDQMC) and floating spherical Gaussian orbitals (FSGO) and spherical Gaussin geminals (SGG) is applied to the H8 model in which the degree of quasi-degeneracy is a function of a single geometrical parameter, a. This random walk based approach has been designated as OUDQMC/FSGO-SGG. The resulting potential energy curve is compared with the corresponding curves obtained by single reference coupled cluster singles and doubles (CCSD) calculation, CCSD calculation with triple excitations non-iteratively, CCSD(T), and Brueckner doubles calculation with triples and quadruples contributions, respectively. The basis set used in the coupled cluster levels of calculations is the quadruple Dunning's correlation consistent basis set (cc-pVQZ).

Poster Session
7:30 PM-10:00 PM, Wednesday, 13 September 2006 Moscone Center -- Hall D, Poster

Division of Physical Chemistry

The 232nd ACS National Meeting, San Francisco, CA, September 10-14, 2006