This paper presents a quantum mechanical approximation to the calculation of thermal rate constants. The rate is derived from a suitable stationary phase approximation to the time integral of the thermal flux-flux correlation function. The goal is to obtain an expression that barely depends on the position of the flux operators, i.e., of the dividing surfaces, so that it can be applied also to complex systems by arbitrarily locating the dividing surfaces. The approach is tested on one and two dimensional systems where quantum effects are predominant over a wide range of temperatures. The results are quite accurate, i.e., within a few percent of the exact values for a reasonable range of dividing surface positions.

A quantum method for thermal rate constant calculations from stationary phase approximation of the thermal flux-flux correlation function integral / C. Aieta, M. Ceotto. - In: THE JOURNAL OF CHEMICAL PHYSICS. - ISSN 0021-9606. - 146:21(2017), pp. 214115.1-214115.14. [10.1063/1.4984099]

A quantum method for thermal rate constant calculations from stationary phase approximation of the thermal flux-flux correlation function integral

C. Aieta
Primo
;
M. Ceotto
Ultimo
2017

Abstract

This paper presents a quantum mechanical approximation to the calculation of thermal rate constants. The rate is derived from a suitable stationary phase approximation to the time integral of the thermal flux-flux correlation function. The goal is to obtain an expression that barely depends on the position of the flux operators, i.e., of the dividing surfaces, so that it can be applied also to complex systems by arbitrarily locating the dividing surfaces. The approach is tested on one and two dimensional systems where quantum effects are predominant over a wide range of temperatures. The results are quite accurate, i.e., within a few percent of the exact values for a reasonable range of dividing surface positions.
rate constant; quantum instanton; tunneling
Settore CHIM/02 - Chimica Fisica
2017
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/2434/504076
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