Second generation wave-function thermostat for ab-initio molecular dynamics

A rigorous two-thermostat formulation for ab-initio molecular dynamics using the fictitious Lagrangian approach is presented. It integrates the concepts of mass renormalization and temperature control for the wave functions. The new thermostat adapts to the instantaneous kinetic energy of the nuclei and thus minimizes its influence on the dynamics. Deviations from the canonical ensemble, which are possible in the previous two-thermostat formulation, are avoided. The method uses a model for the effective mass of the wave functions, which is open to systematic improvement.