The ABINIT Users Mailing List ( CLOSED )

[Matteo Giantomassi <gmatteo@pcpm.ucl.ac.be>]

Dear peng,

On Tue, 2007-03-13 at 21:47 +0800, you peng wrote:
> Dear abinit users,
>       When I used the input file number1 in GW calculation in the
> tutorial, I encountered some problems. I focus on the orthorhombic
> cell ,and I have modified the input parameters in tgw_1.in. But after
> I run abinis,it paused with error. The log file says as follows,
> 
>         DATASET    1 : space group Pn m a (# 62); Bravais oP
> (primitive ortho.)
>  getkgrid : length of smallest supercell vector (bohr)=    3.390926E
> +01
>        Simple Lattice Grid
>  symkpt : found identity, with number  1
> 
>  inkpts : istwfk preprocessed, gives following first values (max. 6):
> 1 1 1 1 1 1
> 
>  chkneu : ERROR -
>   Initialization of occ, with occopt=   1
>   There are not enough bands to get charge balance right
>  Action : modify input file ...
>   (check the pseudopotential charges, the variable charge,
>   and the declared number of bands, nband)
>         
>          But when I increased the nband1,there is also error with
> "bdgw3".     
>  In my case,there are 10 bands occupied.So I set "bdgw3=10  11",and
> "nband1=21". I don't know what's wrong with my input file.

What is the error message you are receving?
I cannot be sure because you didn't send the input file, but I think
that the problem with bdgw is related to the fact that you have to
specify the starting and ending band index for each k point where you
are calculating GW corrections.

For example: 

nkptgw 2
kptgw 0.0 0.0 0.0 
      0.0 0.0 0.5

bdgw  10 11
      10 11


>  Besides,I am not clear with "istwfk1",although I have looked through
> the tutorial and input variables. I don't know how to adjust "istwfk1"
> according to specific cases.

istwfk is used for GS calculations to reduce the number of G vectors 
for particular k-points using time-reversal symmetry (like for example
the Gamma point). 
Unfortunately you cannot take advantage of this symmetry during the
generation of the KSS file and, as a consequence, you have to force
abinit to use all the G vectors for each irreducible k-point.

In a nutshell:

istwfk = 1* (number of irred k-points in the KSS file) 
 
If you don't know the number of irreducible k-points associated to the
k-grid used to generate the KSS file, just run abinit, kill the job
after few seconds and look for the value of nkpt reported in the output
file (only the value of nkpt in the DATASET where the KSS file is
generated)

Once you know the value of nkpt, you can easily modify the value of
istwfk in the input file
 
Hope this helps
Matteo


>        Look forward to your help. Thank you very much.
> 
> 
> yours,
> 
> 
> Friend
> 
> 
> 
> 
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