title: Quantum mechanical single molecule partition function from path integral Monte Carlo simulations.
abstract: 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.
authors.affiliation: Department of Chemical Engineering, University of California-Berkeley, Berkeley, CA 94720, USA.
authors.forename: Shaji
authors.initials: S
authors.lastname: Chempath
authors.forename: Cristian
authors.initials: C
authors.lastname: Predescu
authors.forename: Alexis T
authors.initials: AT
authors.lastname: Bell