[Pw_forum] (no subject)

[Paolo Giannozzi]

On Dec 21, 2009, at 11:17 , yuning wu wrote:

> After got all *.dyn* files, I use the q2r.x to do get *.fc file
> successfully. However, in phdos calculation, I got an error message:
>
>      from frc_blk : error #         1
>      wrong total_weight
>
> I am confused that what can cause this error.

this is something that may occur when the grid of
wavevectors used to calculate the force constant
matrix is "strange", i.e. very small or very elongated.
In PH/matdyn.f90, locate the following line:

                  ! SUM OVER R VECTORS IN THE SUPERCELL - VERY VERY  
SAFE RANGE!

In some cases, it turns out that the VERY VERY SAFE RANGE
is not that safe. Try to increase the coefficients in the preceding
lines:

        DO n1=-2*nr1,2*nr1
            DO n2=-2*nr2,2*nr2
               DO n3=-2*nr3,2*nr3

to something larger, e.g. -4*nr1,4*nr1 and so on. No warranty this
is related to your problem, but it might be

P.
---
Paolo Giannozzi, Dept of Physics, University of Udine
via delle Scienze 208, 33100 Udine, Italy
Phone +39-0432-558216, fax +39-0432-558222