Quantum Mechanical Single Molecule Partition Function from PathIntegral Monte Carlo Simulations
An algorithm for calculating the partition function of a molecule with the path integral Monte Carlo method is presented. Staged thermodynamic perturbation with respect to a reference harmonic potential is utilized to evaluate the ratio of partition functions. Parallel tempering and a new Monte Carlo estimator for the ratio of partition functions are implemented here to achieve well converged simulations that give an accuracy of 0.04 kcal/mol in the reported free energies. The method is applied to various test systems, including a catalytic system composed of 18 atoms. Absolute free energies calculated by this method lead to corrections as large as 2.6 kcal/mol at 300 K for some of the examples presented.
- Research Organization:
- Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
- Sponsoring Organization:
- USDOE Director, Office of Science; National ScienceFoundation
- DOE Contract Number:
- DE-AC02-05CH11231; NSF:CHE-0345280
- OSTI ID:
- 928580
- Report Number(s):
- LBNL-62196; JCPSA6; R&D Project: 4015; BnR: KC0301020; TRN: US200811%%409
- Journal Information:
- Journal of Chemical Physics, Vol. 124, Issue 23; Related Information: Journal Publication Date: 06/21/2006; ISSN 0021-9606
- Country of Publication:
- United States
- Language:
- English
Similar Records
On Achieving High Accuracy in Quantum Chemical Calculations of 3 d Transition Metal-Containing Systems: A Comparison of Auxiliary-Field Quantum Monte Carlo with Coupled Cluster, Density Functional Theory, and Experiment for Diatomic Molecules
Quantum Monte Carlo study of the classical barrier height for the H + H/sub 2/ exchange reaction: restricted versus unrestricted trial functions