Nonadiabatic Molecular Dynamics at Metal Surfaces

Abstract

Dynamics at molecule−metal interfaces are a subject of intense current interest and come in many different flavors of experiments: gas-phase scattering, chemisorption, electrochemistry, nanojunction transport, and heterogeneous catalysis, to name a few. These dynamics involve nuclear degrees of freedom entangled with many electronic degrees of freedom (in the metal), and as such there is always the possibility for nonadiabatic phenomena to appear: the nuclei do not necessarily need to move slower than the electrons to break the Born−Oppenheimer (BO) approximation. In this Feature Article, we review a set of dynamical methods developed recently to deal with such nonadiabatic phenomena at a metal surface, methods that serve as alternatives to Tully's independent electron surface hopping (IESH) model. In the weak molecule−metal coupling regime, a classical master equation (CME) can be derived and a simple surface hopping approach is proposed to propagate nuclear and electronic dynamics stochastically. In the strong molecule−metal interaction regime, a Fokker−Planck equation can be derived for the nuclear dynamics, with electronic DoFs incorporated into the overall friction and random force. Lastly, a broadened classical master equation (BCME) can interpolate between the weak and strong molecule−metal interactions. Here, we briefly review these methods and the relevant benchmarking data, showing in particular how the methods can be used to calculate nonequilibrium transport properties. We highlight several open questions and pose several avenues for future study.

Machine Learning for Electronically Excited States of Molecules

“… 192 − 197 Electron transfer processes as a result of electron–hole-pair excitations can be further investigated along with multiquantum vibrational transitions by discretizing the continuum of electronic states and fitting them (often manually) to reproduce experimental or quantum chemical data in a model Hamiltonian. 183 , 198 − 203 Yet, to the best of our knowledge, the excited electronic states in the condensed phase have not been fitted with ML. A recent review on reactive and inelastic scattering processes and the use of ML for quantum dynamics reactions in the gas phase and at a gas-phase interface can be found in ref ( 204 ).…”

Nonadiabatic quantum dynamics of tribovoltaic effects at sliding metal-semiconductor interfaces

“…Under external stimuli, the accelerated nuclear motion can introduce nonadiabatic electronic transitions between different potential energy surface near the crossing point such that the BO approximation breaks. 23,24 Nevertheless, a basic understanding of the electronic excitation process in an electro-mechanical coupling system is still missing. In this work, a systematic study on the non-adiabatic electronic excitation at a metal/semiconductor sliding interface using quantum dynamics approach is presented, in an effort to shed light on fundamental process and provide instructional guide for materials design and optimization for future semiconductor-based nanogenerators.…”

Analytic Gradients and Derivative Couplings for Configuration Interaction with All Single Excitations and One Double Excitation -- En Route to Nonadiabatic Dynamics

“…to estimate electron transfer rates in singlet fission processes [6], to quantify energy dissipation in gas-metal interfaces [7], to simulate charge recombination in mixed perovskites [8,9], to model photo-induced charge transfer in graphene layers [10] and so on. In order to treat the phenomena above, a host of simulation methods have been proposed and their performance can range from very successful to minimally successful.…”