The second-order Ehrenfest method

摘要: This article describes the Ehrenfest method and our second-order implementation (with approximate gradient Hessian) within a CASSCF formalism. We demonstrate that with predictor–corrector integration improves accuracy of simulation significantly in terms energy conservation. Although is general can be used to study any coupled electron–nuclear dynamics, we apply it investigate charge migration upon ionization small organic molecules, focusing on benzene cation. Using this approach, evolution non-stationary electronic wavefunction for fixed atomic nuclei, where nuclei are allowed move, interplay between them first time. Analysis methods interpretation nuclear dynamics suggested: monitor by calculating spin density system as function