Car-Parrinello molecular dynamics using real space wavefunctions

A Car–Parrinello molecular dynamics implementation using real space discretized wavefunctions on equidistant Cartesian grids is presented. By using numerically discretized Laplace operators of higher order for the evaluation of the electronic kinetic energy as well as for the Poisson equation the total energy expression can be evaluated purely with local operations. Details of our implementation of microcanonical and canonical Car–Parrinello joint dynamics of nuclei and wavefunctions are described. For energy conserving molecular dynamics the exact partial derivatives of the energy expression with respect to the numerical wavefunctions must be available. This aspect is discussed for all contributions to the electronic energy. The crucial point is the efficient iterative solution of the Poisson equation. It is shown that energy conserving dynamics with real space wavefunctions is possible. Our object oriented code is fully parallelized and efficient also for the investigation of systems of realistic size. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)