Beyond ehrenfest: correlated non-adiabatic molecular dynamics

A. P. HORSFIELD; D. R. BOWLER; A. J. FISHER; T. N. TODOROV; C. G. SANCHEZ

JOURNAL OF PHYSICS CONDENSED MATTER

Institute of Physics

Año: 2004 vol. 16 p. 8251 - 8251

0953-8984

method for introducing correlations between electrons and ions that iscomputationally affordable is described. The central assumption is that theionic wavefunctions are narrow, which makes possible a moment expansionfor the full density matrix. To make the problem tractable we reduce theremaining many-electron problem to a single-electron problem by performinga trace over all electronic degrees of freedom except one. This introducesboth one- and two-electron quantities into the equations of motion. Quantitiesdepending on more than one electron are removed by making a Hartree–Fockapproximation. Using the first-moment approximation,we perform a number oftight binding simulations of the effect of an electric current on a mobile atom.The classical contribution to the ionic kinetic energy exhibits cooling and isindependent of the bias. The quantum contribution exhibits strong heating,with the heating rate proportional