On 05/30/2013 05:29 PM, xirainbow wrote: > I changes the pseudopotential from "C.pw-mt_fhi.UPF" to > "C.pz-hgh.UPF" and get the expected "Raman activity" for different > ecutwfc. However, the results of "ecutwfc=110" are still higher than > others. > Compare the output of pw.x at different cutoffs to be sure, my bet is that at that specific value of ecutwfc some symmetry operations are incompatibles with the FFT grid. It can make convergence harder. In general, I found that when you have problems converging response (phonon, epsilon, raman...) calculations it's better to use a much stricter conv_thr (i.e. 1.d-12). Sometimes I even reduce the hard-coded threshold (ethr) in PHonon/PH/set_defaults_pw.f90
bests -- Dr. Lorenzo Paulatto IdR @ IMPMC -- CNRS & Universit? Paris 6 phone: +33 (0)1 44275 084 / skype: paulatz www: http://www-int.impmc.upmc.fr/~paulatto/ mail: 23-24/4?16 Bo?te courrier 115, 4 place Jussieu 75252 Paris C?dex 05
