[Pw_forum] Negative values in density matrix.

Lorenzo Paulatto lorenzo.paulatto at impmc.upmc.fr
Tue Oct 9 19:50:22 CEST 2012

On 9 October 2012 19:12, <jorge.gallardo at cab.cnea.gov.ar> wrote:

> > Dear Jorge,
> >  I do not understand what you are trying to do. In particular, nr1, nr2
> > and
> > nr2 have nothing to do with defining a supercell: you should not change
> > them except in very special cases.
 Yes, they are just numerical errors: vacuum is composed as a linear
combination of plane waves which never cancel out exactly.

BTW, instead of changing nrX, you would get the same result using ecutrho.
The two methods are mostly equivalent but not exactly, it is probably safer
and faster (computationally) to use ecutrho instead of nrX.

Dr. Lorenzo Paulatto
IdR @ IMPMC -- CNRS & Université Paris 6
phone: +33 (0)1 44275 084 / skype: paulatz
www:   http://www-int.impmc.upmc.fr/~paulatto/
mail:  23-24/4é16 Boîte courrier 115, 4 place Jussieu 75252 Paris Cédex 05
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