[Pw_forum] internal parameter 'u'

[Stefano de Gironcoli]

I think the simplest way to specify the internal parameter is to  choose 
to define the structure using crystal coordinates and specify them 
according to what is reported in the wyckoff books on crystal structure.
stefano

 
kajal jindal wrote:
> Hello Sir,
>
> Thanks for replying to my query ..but I actually want to specify the 
> value of 'u' in my input file in the same way as we specify the cell 
> parameters and then optimize its value and get the optimized value of 
> 'u' in my output file..Is it possible to do so???and how?????
>
> Thanks a lot,
>
> Miss Kajal,
> UTA(University Of Delhi).
>
> On Sat, Jan 16, 2010 at 9:33 PM, Stefano de Gironcoli 
> <degironc at sissa.it <mailto:degironc at sissa.it>> wrote:
>
>     you need to perform a structural relaxation that includes both the
>     cell
>     and the internal degrees of freedom
>     calculation='vc-relax' is what you want, then you need to specify the
>     &cell namelist. cell_dynamics='bfgs' (default) should be ok.
>     stefano
>
>     kajal jindal wrote:
>     > Hii,
>     >
>     > I discussed this problem before also but was not much clear..So i m
>     > discussing it again..Actually I want to know that what inputs do I
>     > need to specify in my input file to optimize the value of internal
>     > parameter 'u', which characterizes the length of the bond
>     parallel to
>     > c-axis, in hexagonal wurtzite structure ..
>     >
>     > Thanks in advance,
>     >
>     > sincerely,
>     > Miss Kajal
>     > (UTA)(University of Delhi)
>     >
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