A general and efficient Monte Carlo method for sampling intramolecular degrees of freedom of branched and cyclic molecules
Abstract
A simple and easily implemented Monte Carlo algorithm is described which enables configurational-bias sampling of molecules containing branch points and rings with endocyclic and exocyclic atoms. The method overcomes well-known problems associated with sequential configurational-bias sampling methods. A “reservoir” or “library” of fragments are generated with known probability distributions dependent on stiff intramolecular degrees of freedom. Configurational-bias moves assemble the fragments into whole molecules using the energy associated with the remaining degrees of freedom. The methods for generating the fragments are validated on models of propane, isobutane, neopentane, cyclohexane, and methylcyclohexane. It is shown how the sampling method is implemented in the Gibbs ensemble, and validation studies are performed in which the liquid coexistence curves of propane, isobutane, and 2,2-dimethylhexane are computed and shown to agree with accepted values. The method is general and can be used to sample conformational space for molecules of arbitrary complexity in both open and closed statistical mechanical ensembles.
Document Details
- Document Type
- Pub Defense Publication
- Publication Date
- Oct 07, 2011
- Source ID
- 10.1063/1.3644939
Entities
People
- Edward J. Maginn
- Jindal K Shah
Organizations
- Air Force Office of Scientific Research
- National Science Foundation
- University of Notre Dame