Ehrenfest dynamics with quantum mechanical nuclei

Abstract

With the aid of simple “toy models”, we evaluate the performance of the Ehrenfest method for molecular dynamics simulation in cases where some atomic nuclei are designated as classical and others quantum mechanical. Whereas the underlying formalism of the method is the same as when all the nuclei are treated classically and only the electrons by quantum mechanics, the mass disparity between classical and quantum particles is nearly eliminated when some of the nuclei are treated quantum mechanically, with significant consequences to accuracy and usefulness.