EPJ B – A step up in the game of electron-ion dynamics simulations

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Published on 10 November 2010

A Colloquium paper by McEniry et al. published in EPJ B surveys the theory and applications of a new family of computational methods, namely Correlated Electron-Ion Dynamics, which enable the simultaneous evaluation of the electronic current, along with the current-induced forces and subsequent motion of the nuclei.

The classic method to investigate the non-adiabatic exchange of energy between electrons and nuclei is Ehrenfest Dynamics. It is simple and most efficient to implement but it’s unable to capture the effects of inelastic scattering of electrons and the subsequent motion of the atoms. A new Correlated Electron-Ion Dynamics (CEID) approximation has been developed to deal with quantum interference. For weak electron-phonon coupling, the mean field second moment approximation has been found to be very useful, though it can suffer from stability problems. However it is currently the method of choice for including inelastic effects in transport simulations of nanostructures. When the electron-phonon interaction is strong (as occurs in conjugated polymers) there is a higher order CEID formalism available. The robustness and systematic extensibility of this approach allows one to follow the coherent motion of electrons and nuclei.