[Pw_forum] unexpected force_symmorphic behavior with explicit k grid

[Paolo Giannozzi]

On Wed, 2012-06-20 at 17:46 +0200, Giovanni Pizzi wrote:

> I was using the force_symmorphic flag of pw.x.

you shouldn't, unless you have a good reason to use it

> I noticed that even when I provide an explicit list of k points 
> (e.g. with
> K_POINTS crystal
> or even
> K_POINTS crystal_b
> for a band structure) pw.x increases the number of k points.

"force_symmorphic" just removes the symmetry operations having
an associated fractional translation from the list of allowed
symmetries. Any change in the number of k-points, if any, is 
a consequence of the reduced symmetry of the system.

> Is this the intended behavior, or should the list of K points be 
> modified only for K_POINTS automatic?

hard to say what the "intended" behavior is: there isn't any.
That option was added (by me) in order to allow PWscf to produce
data for other codes (don;t remember which ones) that do not 
implement nonsymmorphic symmetry groups.

P.
-- 
Paolo Giannozzi, IOM-Democritos and University of Udine, Italy