Nonadiabatic molecular dynamics simulation of photodissociation and geminate recombination of I2 liquid xenon

Abstract

In this paper we investigate the B state predissociation and subsequent geminate recombination of photoexcited iodine in liquid xenon using a coupled quantum-classical molecular dynamics method and a model Hamiltonian gained from the diatomics-in-molecules semiempirical approach to excited state electronic structure including spin-orbit coupling. We explore the capabilities of these techniques as applied to studying the dynamics of realistic condensed phase reactions by comparing with available experimental data from recent ultrafast spectroscopic studies and Raman scattering measurements. We present a microscopic understanding of how the solvent perturbs the electronic states of the chromophore and opens various channels for dissociation from the bound excited B state. We survey the different possible dissociative channels and determine their relative importance as a function of solvent density. We find that predissociation usually occurs during the first bond extension within about 50-100 fs. We follow our trajectories out to 2 ps and observe early solvent collisions which, at the highest solvent densities studied, often result in geminate recombination to the excited bound AЈ state with in this time.

The infrared-driven cis–trans isomerization of nitrous acid HONO III: A mixed quantum–classical simulation

“…Mixed quantum-classical simulations have been performed by various groups [32][33][34][35][36][37][38][39][40][41][42][43], and have been applied to both electronic transitions [37,38] as well as hydrogen transfer reactions [42]. Two concepts dominate the literature: mean-field molecular dynamics and surface hopping techniques [36].…”

Theoretical simulations of the He79Br2 B, v=8←X, v″=0 excitation spectrum: Spectroscopic manifestation of a linear isomer?

“…It was noted 43,44 that there are two such functions of 0 g ϩ symmetry correlating to the ground 2 P 3/2 ϩ 2 P 3/2 dissociation limit. In terms of ͉ jm͘ ␣ functions of bromine atoms, they can be expressed as 43,44,46 …”

A classical molecular dynamics study of recombination reactions in a microporous solid

“…Inclusion of the curve-crossing dynamics into the simulation would be necessary in order to predict details of the recombination process, as it is well known that the iodine geminate recombination results from multiple crossings of excited electronic surfaces. 18 Recently, methods for incorporating electronic transitions in molecular dynam-ics simulations have been developed, 19 but they are demanding of computer resources, and we preferred to model the recombination as occurring on a single electronic surface. This strong simplification allows much longer simulation times, which are required to reach the main purpose of our study.…”