Comparison between the analysis of the asymptotic wavepacket and the associated flux for the calculation of kinetic‐energy‐releases function

• Published in: International journal of quantum chemistry Vol. 119; no. 7
• Main Author: Han, Yong‐Chang
• Format: Journal Article
• Language: English
• Published: Hoboken, USA John Wiley & Sons, Inc 05.04.2019; Wiley Subscription Services, Inc
• Subjects: Asymptotic methods; Asymptotic properties; Chemistry; Distribution functions; Eigenvectors; Energy distribution; Flux; kinetic‐energy‐releases; Mathematical analysis; Molecular dynamics; photodissociation; Physical chemistry; Projection; Quantum physics; quantum wavepacket; time‐dependent Schrödinger equation
• ISSN: 0020-7608; 1097-461X
• DOI: 10.1002/qua.25858

The kinetic‐energy‐releases (KER) distribution function of the fragment is an important observable in the molecular dynamics. In theory, there are several different methods to calculate the KER distribution function or spectrum, which could be generally divided into two classes: One is based on the analysis of the asymptotic wavepacket (“projection method”) and the other is on the analysis of the associated flux (“flux method”). By taking the above‐threshold dissociation of the HeH+ (v = 8) molecule as an example, we compared these two classes of methods. Based on evenly separated Fourier grid representation, the KER distribution calculated via the projection method FProj(Ek) is the same as the one calculated via the flux method FFlux(Ek). The relationship between FProj(Ek) and the distribution of the projection of the asymptotic wavepacket onto the energy eigenstates of the quasicontinuum, PProj(Ek), and the relationship between FFlux(Ek) and the distribution of the dissociation probability PFlux(Ek) from the cumulation of the associated flux, are determined. The kinetic‐energy‐releases (KER) distribution of the fragments is one of the most important. observables in experiment for us to understand the relevant molecular dynamics, such as the photodissociation, photoionization, or chemical reaction collision. By taking the above‐threshold dissociation of HeH+ (v = 8) as model, the projection method and the flux method for the calculation of KER distribution function F (E k) have been compared.