[Pw_forum] shift kpoint
Lorenzo Paulatto
paulatto at sissa.it
Fri Aug 21 11:28:30 CEST 2009
In data 21 agosto 2009 alle ore 11:22:20, ali kazempour
<kazempoor2000 at yahoo.com> ha scritto:
> Dear all
> In principle ,where the shift of kpoints is important? I mean which
> information should we loose when we don't use from shift in our kpoint
> mesh?
You don't loose any information, it's just that a shifted grid makes the
calculation converge faster w.r.t the number of kpoints. This is normally
only true after applying symmetry operation to reduce the number of
kpoints.
> [...] does it mean that symmetry reduces this set to a set of points in
> the irreducible part of BZ?
Exactly.
There are some exceptions though, e.g. using Gamma point (and only Gamma
point) is the only meaningful choice for isolated systems.
regards
--
Lorenzo Paulatto
SISSA & DEMOCRITOS (Trieste)
phone: +39 040 3787 511
skype: paulatz
www: http://people.sissa.it/~paulatto/
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