On Feb 6, 2009, at 1:14 AM, Timothy Mason wrote: > > Dear Stefano, > >>> ii) some noise comes >in unporposedly, because of numerical >>> accuracy >>(this is often coped is, >again as suggested by >>> Gabriele, by explicitly >>>simmetrizing the resulting >forces), > > does this imply that a good fix to the checkallsym error in vc-relax > is to increase ecut to avoid numerical errors that would break the > symmetry during vc-relax?
I do not think so. I confess not to know what the "checkallsym error" is, but any errors done by reducing the basis set cannot break any symmetry. I was rather referring to small roundoff errors that may accumulate during the computation. Stefano --- Stefano Baroni - SISSA & DEMOCRITOS National Simulation Center - Trieste http://www.sissa.it/~baroni / [+39] 040 3787 406 (tel) -528 (fax) / stefanobaroni (skype) La morale est une logique de l'action comme la logique est une morale de la pens?e - Jean Piaget 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/20090206/98053318/attachment.htm
