Timo: I do not have a solution handy, and others may have deeper ideas. I think the problem is that when simmetrizing the charge density the code always assumes e(k)=e(-k) and psi(-k)=psi(k)*, and so it never uses more than 1/2 the BZ. One thing you may try is to pass explicitly all the k-points, and wish that the code is not so smart as to remove 1/2 of them ... Otherwise, I do not see any other options than hacking the code (but, again, others may have smarter ideas). SB
On Nov 21, 2007, at 4:04 AM, Timo Thonhauser wrote: > Dear All, > > I have a question concerning the breaking of time-reversal symmetry > within PWscf. For my proposes I have modified the code and included a > (periodic) vector potential into the Hamiltonian. The code gives very > good results for the quantity that I am interested in for molecules, > i.e. gamma-point calculations. However, when I try to do calculations > for periodic solids, the results worsen. > > I think the code (unless you do spin-orbit coupling) assumes time- > reversal symmetry. In principle, including a vector potential breaks > time-reversal symmetry. But, in the cases of my gamma-point > calculations > that did not cause any problems ( psi_(-k)=psi_(k)* for k=gamma ) and > hence, I get good results for molecules. However, maybe this is the > problem with my calculations for extended systems: including the > vector potential breaks time-reversal symmetry, and > in general psi_(-k) is not psi_(k)*, but the code is not "aware" > that the symmetry has been broken. > > Thus, my question is: is there a simple way to tell the code that > time-reversal symmetry is broken without getting into spin-orbit > stuff? > > Thanks, > Timo Thonhauser, MIT > > ______________________________________________________________________ > > Dr. TIMO THONHAUSER > Department of Materials Science and Engineering (617) 253 6026 > MIT, 13-4084, 77 Massachusetts Avenue thonhauser at mit.edu > Cambridge, MA 02139-4307, USA www.mit.edu/~thonhaus > ______________________________________________________________________ > > > _______________________________________________ > Pw_forum mailing list > Pw_forum at pwscf.org > http://www.democritos.it/mailman/listinfo/pw_forum --- Stefano Baroni - SISSA & DEMOCRITOS National Simulation Center - Trieste [+39] 040 3787 406 (tel) -528 (fax) / stefanobaroni (skype) Please, if possible, don't send me MS Word or PowerPoint attachments Why? See: http://www.gnu.org/philosophy/no-word-attachments.html -------------- next part -------------- An HTML attachment was scrubbed... URL: http://www.democritos.it/pipermail/pw_forum/attachments/20071121/b566c291/attachment-0001.htm
