[Wien] berryphase

[Shahrbano Raheme]

Dear Prof. Rubel and Prof. Sheikh,

> 1) Take the structure files enclosed (I assume they are not different from yours).
I used your stature file and found that it is identical to my structure.

>Please, make sure that you have the latest version of WIEN2WANNIER (see the post http://www.mail-archive.com/wien@zeus.theochem.tuwien.ac.at/msg09119.html).

> My computed effective charge seems to almost the same as computed by Dr. Rubel. I think you are using older versions of either BerryPI or Wien2Wannier or both. Please use the latest version of BerryPI (v1.0) https://github.com/spichardo/BerryPI and Wien2Wannier (v0.97) http://www.wien2k.at/reg_user/unsupported/wien2wannier/.The older version of BerryPI (v0.1) had some problem in wrapping of phases 
which has been fixed in version 1.0. Also, the older versions of 
Wien2wannier was having an issue in identifying the complex calculation (see the post http://www.mail-archive.com/wien@zeus.theochem.tuwien.ac.at/msg09119.html)

I installed the latest version of BerriPI, WIEN2WANNIER, WANNIER90, 
NUMPHY, and could reproduce the results of Prof. Rubel in agreement with reported values in literature. But, we still do not know what was the 
source of problem of the BerryPI or WIEN2WANNIER old version which resulted in an unsatisfactory result. We are interested in realizing the bug(s)  of the old version(s).
 
> 2) create directories 'lambda1' and 'lambda2'. In both cases I displace the Ga atom by +0.01 and -0.01 along z-axis. There is nothing specific 
about the choice of displacements. In fact 0.005 should work too. I 
encourage you to test the convergence and plot Z as a function of 
displacement. I do not recommend to go for displacements larger than 
0.01


I did it, and the results which nicely confirm your prediction, do not depend on the Z.

Now I am working on your following comments:

> In order to address the spontaneous polarization, we need two cases:
(a) the initial reference structure and
(b) your relaxed structure.
The spontaneous polarization is the difference between them. Please, 
look in the literature what is used as a reference structure. The choice
 of structure (a) for GaN is not obvious to me. Once you determine that,
 I can help you to move on.

Would you give me some clue to reach the goal sooner? 

PS: We detected that init.sh ha a bug. If the version of the installed 
numpy is 1.6.2, the init.sh works fine. But, if the version is different depending on the linux version, e.g., numpy 1.4.1, then init.sh script 
tries to install numpy 1.6.2 on .local directory. This is not necessary, as already bumpy 1.4.1 is installed. Although the installation on 
.local directory is successful by init.sh, but init.sh cannot uses it, 
because it is not installed in the default path. So, for such a case, we changed 1.6.2 to 1.4.1 in init.sh to prevent its stop in changing the 
.bashrc automatically. We just thought that you maybe in next version 
would like to fix this small bug.
 Thank you for your attentions,
SH.Rahimi
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