Photo-induced reactions from efficient molecular dynamics with electronic transitions using the FIREBALL local-orbital density functional theory formalism

摘要

The computational simulation of photo-induced processes in large molecularsystems is a very challenging problem. Here, we present a detailed descriptionof our implementation of a molecular dynamics with electronic transitionsalgorithm within the local-orbital density functional theory code Fireball,suitable for the computational study of these problems. Our methodology enablessimulating photo-induced reaction mechanisms over hundreds of trajectories;therefore, large statistically significant ensembles can be calculated toaccurately represent a reaction profile. As an example of the application ofthis approach, we report results on the [2+2] cycloaddition of ethylene withmaleic anhydride and on the [2+2] photo-induced polymerization reaction of twoC60 molecules. We identify different deactivation channels of the initialelectron excitation, depending on the time of the electronic transition fromLUMO to HOMO, and the character of the HOMO after the transition.