2006年2月
Path-integral virial estimator for reaction-rate calculation based on the quantum instanton approximation
JOURNAL OF CHEMICAL PHYSICS
- ,
- ,
- 巻
- 124
- 号
- 8
- 記述言語
- 英語
- 掲載種別
- 研究論文(学術雑誌)
- DOI
- 10.1063/1.2171693
- 出版者・発行元
- AMER INST PHYSICS
The quantum instanton approximation is a type of quantum transition-state theory that calculates the chemical reaction rate using the reactive flux correlation function and its low-order derivatives at time zero. Here we present several path-integral estimators for the latter quantities, which characterize the initial decay profile of the flux correlation function. As with the internal energy or heat-capacity calculation, different estimators yield different variances (and therefore different convergence properties) in a Monte Carlo calculation. Here we obtain a virial (-type) estimator by using a coordinate scaling procedure rather than integration by parts, which allows more computational benefits. We also consider two different methods for treating the flux operator, i.e., local-path and global-path approaches, in which the latter achieves a smaller variance at the cost of using second-order potential derivatives. Numerical tests are performed for a one-dimensional Eckart barrier and a model proton transfer reaction in a polar solvent, which illustrates the reduced variance of the virial estimator over the corresponding thermodynamic estimator.
- リンク情報
- ID情報
-
- DOI : 10.1063/1.2171693
- ISSN : 0021-9606
- eISSN : 1089-7690
- Web of Science ID : WOS:000235663300009