chenjie gu wrote: > for ion_temperature=andersen: the collision frequency parameter is given > as nu=1/tau defined above
"above", in the documentation, you find the following definition: tau = nraise*dt. "nraise" is an integer of your choice; dt is the time step. So the collision frequency parameter nu of the Andersen thermostat is nu=1/(nraise*dt), or, in a more transparent way, nu*dt = 1/nraise, that is, every nraise time steps there is a "collision", i.e. the velocity of one randomly selected particle gets a random value, distributed according to the maxwellian distribution for temperature T (I hope I remember correctly how the Andersen thermostat works). The way the various thermostats in pw.x are introduced is a confusing because the same parameter "nraise" has different meanings for different thermostats. P. -- Paolo Giannozzi, Democritos and University of Udine, Italy
