TIME-REVERSIBLE MULTIPLE TIME-SCALE AB-INITIO MOLECULAR-DYNAMICS

We have developed previously ab initio molecular dynamics (AIMD) algor ithms utilizing local molecular wave functions with atom-centered base s. The expense of such methods led us to explore means to employ multi ple time step schemes to reduce costs. Herein we report our second imp lementation of such a scheme. Tn particular, our previous multiple tim e step AIMD method has been improved substantially by the implementati on of the time-reversible reference system propagator algorithm (RESPA ) of Berne and co-workers. The time-reversible version of RESPA treats multiple time steps rigorously without introducing the limitations in herent in our previous non-time-reversible AIMD RESPA implementation. We are thus simultaneously able to obtain substantial additional savin gs in computer time and to maintain high accuracy, as shown in test ca lculations on a sodium cluster.