Mixed time slicing in path integral simulations
- Department of Chemistry, Yale University, New Haven, Connecticut 06405 (United States)
A simple and efficient scheme is presented for using different time slices for different degrees of freedom in path integral calculations. This method bridges the gap between full quantization and the standard mixed quantum-classical (MQC) scheme and, therefore, still provides quantum mechanical effects in the less-quantized variables. Underlying the algorithm is the notion that time slices (beads) may be 'collapsed' in a manner that preserves quantization in the less quantum mechanical degrees of freedom. The method is shown to be analogous to multiple-time step integration techniques in classical molecular dynamics. The algorithm and its associated error are demonstrated on model systems containing coupled high- and low-frequency modes; results indicate that convergence of quantum mechanical observables can be achieved with disparate bead numbers in the different modes. Cost estimates indicate that this procedure, much like the MQC method, is most efficient for only a relatively few quantum mechanical degrees of freedom, such as proton transfer. In this regime, however, the cost of a fully quantum mechanical simulation is determined by the quantization of the least quantum mechanical degrees of freedom.
- OSTI ID:
- 21560018
- Journal Information:
- Journal of Chemical Physics, Vol. 134, Issue 7; Other Information: DOI: 10.1063/1.3518714; (c) 2011 American Institute of Physics; ISSN 0021-9606
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
GENERAL PHYSICS
74 ATOMIC AND MOLECULAR PHYSICS
37 INORGANIC
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
ALGORITHMS
COST
DEGREES OF FREEDOM
ERRORS
MOLECULAR DYNAMICS METHOD
PATH INTEGRALS
PROTONS
QUANTIZATION
QUANTUM MECHANICS
SIMULATION
STANDARDS
BARYONS
CALCULATION METHODS
ELEMENTARY PARTICLES
FERMIONS
HADRONS
INTEGRALS
MATHEMATICAL LOGIC
MECHANICS
NUCLEONS