$Ab\ initio$ molecular dynamics of temporary anions using complex absorbing potentials

TL;DR

This paper introduces a new ab initio molecular dynamics method using complex absorbing potentials to simulate temporary anions and dissociative electron attachment, providing mechanistic insights and qualitative agreement with experiments.

Contribution

The paper develops a novel computational approach for simulating the dynamics of temporary anions on complex potential energy surfaces using Hartree-Fock theory with complex absorbing potentials.

Findings

Qualitative agreement with experimental dissociative electron attachment data

Method handles molecules undergoing dissociation and autodetachment equally well

Provides mechanistic insights into electron-induced bond cleavage

Abstract

Dissociative electron attachment, that is, the cleavage of chemical bonds induced by low-energy electrons, is difficult to model with standard quantum-chemical methods because the involved anions are not bound but subject to autodetachment. We present here a new computational development for simulating the dynamics of temporary anions on complex-valued potential energy surfaces. The imaginary part of these surfaces describes electron loss, whereas the gradient of the real part represents the force on the nuclei. In our method, the forces are computed analytically based on Hartree-Fock theory with a complex absorbing potential. $Ab\ initio$ molecular dynamics simulations for the temporary anions of dinitrogen, ethylene, chloroethane, and the five mono- to tetrachlorinated ethylenes show qualitative agreement with experiments and offer mechanistic insights into dissociative electron attachments. The results also demonstrate how our method evenhandedly deals with molecules that may undergo dissociation upon electron attachment and those which only undergo autodetachment.