On Jan 8, 2012, at 17:43 , Caloma Trumica wrote: > why do we need to have such an additional setting of q points > rather than just using k points mesh for both?
because they refer to different quantities and have different convergence criteria. The "k-point" grid is used to perform the integral over the Brillouin Zone; the "q-point" grid is used to perform integrals over phonon wave vectors, or to obtain Interatomic Force Constants in real space. P. --- Paolo Giannozzi, IOM-Democritos and University of Udine, Italy "Nothing is impossible for the man who doesn't have to do it himself"
