[Wien] berryphase

[Oleg Rubel]

Dear Shahrbano


> ... But, we still do not know what is the role of "*" in tmp="$(grep
> "lapw1 *-c" "$SEEDNAME.dayfile")". As far as I know –c flag is necessary
> when inversion symmetry is break down and complex calculations are needed to
> be performed by the WIEN2k code. I am not aware about "*-c" flag.

The star was need to account for an arbitrary number of spaces
proceeding '-c' flag. Please, check 'grep' manual for details. The
newer version of W2W uses even more robust check for '-c' flag.


> We are also not sure whether it is referred to the relaxed and unrelaxed
> structures. Thus, we tried to check it out. To do this, we selected the
> unrelaxed structure for lambda1and the relaxed one for lambda0. Our result
> is as follows:
> 3.16596720935 - 3.17586420101 = -0.00989699166
>
> But, this result is far from reported value in the literature, i.e., SP was
> reported to be -0.02 [PRB86, 081302(R) and PRB56, R10024].

A quick glance at these references shows that they are discussing zinc
blende structure as a zero-polarization reference. So you probably
need to make a zinc blende GaN is the same fashion as wurtzite
structure. Fig. 12 in [Physics Reports, Volume 428, Issue 1, May 2006,
Pages 1-52] will be a good starting point, but still not exactly what
you need. At the end both structures should have identical symmetry
and the same # of atoms.


> Does this mean that one has to try by changing the displacement reproduce
> the experimental value? In this case our result depends on the displacement.
> Can it be (in this case) an ab initio prediction?

No... please disregard this for now.


> Yes, NUMPY 1.4.1 works as fine as NUMPY 1.6.2.

Good to know.


Thank you
Oleg