On Tue, July 7, 2009 08:27, oulihui666 wrote: > Thus, I'd like to ask if PWSCF can do calculations that vacuum layer do > not fill backgrount charges ?
The system is not really filled with background charges, what is really done is actively set the G=0 component of V to zero. In this way the average value of the potential over the unit cell is zero, and everything works fine (if you can afford a cell big enough to suppress periodic image interaction) > I have checked the manual and original pipemails, but didn't find many > topics on background charges. There are a few, e.g. <http://www.democritos.it/pipermail/pw_forum/2005-April/002379.html> > However,I found many discussions on EXTERNAL POTENTIAL which makes it > possible to add an external electrostatic field. > If possible, how ? Have a look at the documentation, Doc/INPUT_PW.html; there are two ways to do it: using a sawtootk potential or using the modern theory of polarization (Berry phase); the latter is only implemented for insulators. > > Many thanks. best regards -- Lorenzo Paulatto SISSA & DEMOCRITOS (Trieste) phone: +39 040 3787 511 skype: paulatz www: http://people.sissa.it/~paulatto/ ---------------------------------------------------------------- SISSA Webmail https://webmail.sissa.it/ Powered by SquirrelMail http://www.squirrelmail.org/
