Capturing the photo-induced dynamics of nano-molecules by X-ray free electron laser induced Coulomb explosion

Dissociation mechanism from highly charged bromophenol: ab initio molecular dynamics simulations

Dissociation mechanisms are studied by ab initio molecular dynamics simulations based on density functional theory for the highly charged bromophenol (C6H4OHBr)n+ (n ≤ 10) in the ground electronic state and in an electronic state which has a high electronic temperature Te characterized by Fermi–Dirac distribution. In the case of the ground state, the dissociation occurs through a sequential multi-stage process. At times shorter than 20 fs after the molecule is charged, hydrogens are dissociated from the molecule and, subsequently, the carbon ring breaks at about 150 fs In the case of an electronic state with high Te, the mechanism changes from a sequential dissociation process to a simultaneous process occurring at Te > 5 eV. To estimate the charge transfer time in a molecular bromide parent ion with +6 charge, which is generated through Auger cascades, we also performed nonadiabatic quantum-mechanical molecular dynamics (NAQMD) simulations that include the effects of nonadiabatic electronic transition with a surface-hopping approach.