[Pw_forum] q2r.x for a perticular q-point

[Bipul Rakshit]

HI stefano,
Thanks for your kind reply.
I just thought that after using q2r.x and matdyn.x the frequencies in
different q points are little bit modified (changed), as they are in
*.dyn file.


On 1/17/10, Stefano de Gironcoli <degironc at sissa.it> wrote:
> Dear Bipul Rakshit,
>  q2r.x is used to generate an interatomic-force constant file (to be
> used with matdyn.x) from a set of matrices corresponding to a
> gamma-centered regular grid of points in the BZ.
>   the single K point does not belong to the 1x1x1 grid nor it forms a
> complete 6x6x1 grid... hence the error messages you get.
>   ph.x does however compute the frequencies at the end of the run ... so
> what need do you have for q2r.x+matdyn.x ?
>   stefano
>
>
> Bipul Rakshit wrote:
>> Dear PWSCF user,
>> I am doing phono calculation of graphene sheet.
>> If i just want to calculate the frequencies at K point (0.333330
>> 0.577350  0.000000
>> ) i am using the following input files
>>
>>
>> *phonons of Graphene
>>  &inputph
>> ! recover =.true.,
>>   tr2_ph=1.0d-14,
>>   alpha_mix(1)=0.4,
>>   prefix='graphene',
>>   amass(1)=12.0107,
>>   outdir='./OUT',
>>   fildyn='Graph.dyn2',
>> !  epsil= .true.,
>> !  trans= .true.,
>> !  ldisp=.true.
>> !  nq1=6, nq2=6, nq3=1
>>  lnscf=.true.,
>> /
>> 0.333330  0.577350  0.000000
>> *
>>
>>
>> and q2r.in <http://q2r.in> as
>>
>> * &input
>>     zasr='crystal', flfrc='Graph.fc'
>>  /
>> 1 1 1
>> 1
>> Graph.dyn2
>> /*
>>
>> after using q2r.x it gives the error q not allowed, but instead of 1 1
>> 1 if i use 6 6 1, then it gives error 'q point(s) missing'
>>
>> So is it possible to get the correct phonon frequencies of some
>> individual q-point (in my case K), after using the q2r.x
>> and if its possible. Kindly tell me how the inputs should be modified
>>
>> --
>> Bipul Rakshit
>> Research Fellow,
>> S N Bose Centre for Basic Sciences,
>> Salt Lake,
>> Kolkata 700 098
>> India
>>
>>
>> --
>> Dr. Bipul Rakshit
>> Research Associate,
>> S N Bose Centre for Basic Sciences,
>> Salt Lake,
>> Kolkata 700 098
>> India
>> ------------------------------------------------------------------------
>>
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>
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-- 
Dr. Bipul Rakshit
Research Associate,
S N Bose Centre for Basic Sciences,
Salt Lake,
Kolkata 700 098
India