[Pw_forum] possible bug in scatter_forw.f90

[Manoj Srivastava]

Any follow ups on the message below? Alexander? 

Regards, 
Manoj
On Wed, 8 Oct 2008, Manoj Srivastava wrote:

> 
> Dear All, 
>  Is any body familiar with the scatter_forw.f90 subroutine of PWCOND? I
> think there is a bug in this subroutine at the place where you calculate
> intw2, which is z integration of nonlocal wavefunction with beta function.
> I have looked up the necessary formulae in the Choi & Ihm's paper (PRB 59,
> 2267, Jan 1999). In the paper, nonlocal wavefunction has 3 terms, one of
> which contains beta function, say W. The other two parts dont have any W
> in them, rather they are just plane wave solution. (Please have a look at
> equation 24 and 26 of the paper ). So, when we are doing z integration of
> nonlocal wavefunction with beta function W, we should have three terms,
> one of which should contain two W, but rest should just have one W. On the
> other hand in the code all three terms contain two beta functions!!
> (please have a look at line 228 of scatter_forw.f90). I am wondering if my
> understanding is right? 
> I have one more question in the later part of the same subroutine. What
> does the lapack subroutine 
> ZGESV(2*n2d,2*n2d+norb*npol,amat,2*n2d,ipiv,xmat,2*n2d,info)
> do? 
> I tried to look it up and i got the idea that it is trying to solve 
> amat*x=xmat, with amat and xmat known and x unknown, and at the end of
> calculation it stores x in xmat. 
> so, basically it does--  x=[(amat)^(-1)]*xmat. Am i right? So, it changes
> the structure of xmat from what is defined in 'constructs matrices'
> part. Is it correct? 
> Also, afterwards in this code where  it 'rotates integrals' is not very
> clear to me. 
> Could somebody please tell me in little detail, what is going on
> here? Also, is this subroutine written just on the basis of Choi and Ihm
> paper, or are there more reference to it? If yes, would someone mind
> mentioning them? 
> 
> Regards, 
> Manoj Srivastava 
> Physics Graduate Student 
> University of Florida, 
> Gainesville,FL, USA
> 
>