Thanks SIr, i will study Yambo or Sax. <br>Thanks,<br>Yours sincerely,<br>Dev ,<br>University of Delhi,<br><br><br><div class="gmail_quote">On Mon, Oct 12, 2009 at 3:59 PM, <span dir="ltr"><<a href="mailto:marsamos@democritos.it">marsamos@democritos.it</a>></span> wrote:<br>
<blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;">Dear User, for generating a kpoint grid supported by epsilon you can<br>
use the following small program (for pwscf input you have to specify<br>
nosym=.true., and KPOINTS crystal)<br>
<br>
program kpoints_gen<br>
<br>
integer :: ikz, iky, ikx, nk<br>
real :: weight<br>
real :: shiftx, shifty, shiftz<br>
<br>
read(*,*) nkx, nky, nkz, shiftx, shifty, shiftz<br>
<br>
nk=nkx*nky*nkz<br>
weight=1.0/real(nk)<br>
write(*,*) nk<br>
do ikz=1,nkz<br>
do iky=1,nky<br>
do ikx=1,nkx<br>
<br>
write(*,"(4f15.9)") (real(ikx)-real(1.0)+shiftx)/real(nkx),<br>
(real(iky)-real(1.0)+shifty)/real(nky), &<br>
(real(ikz)-real(1.0)+shiftz)/real(nkz), weight<br>
<br>
enddo<br>
enddo<br>
enddo<br>
<br>
<br>
end program kpoints_gen<br>
<br>
<br>
BUT I strongly suggest to you to use or the utilities inside SaX (see<br>
<a href="http://www.sax-project.org" target="_blank">www.sax-project.org</a>) or yambo (<a href="http://www.yambo-code.org" target="_blank">www.yambo-code.org</a>) for calculating the<br>
dielectric constant. epsilon.x is not complete (it does not include the<br>
nonlocal part of the pseudo potential and is not able to include in the<br>
calculation the non-local field effects and excitonic effects). If YOU<br>
WORK WITH SEMICONDUCTORS OR INSULATORS YOU WILL NOT BE ABLE TO COMPARE<br>
WITH EXPERIMENTS. You should now which kind of RESPONSE you want to<br>
reproduce.<br>
<br>
bests<br>
<br>
layla<br>
<div><div></div><div class="h5"><br>
<br>
<br>
Quoting Gabriele Sclauzero <<a href="mailto:sclauzer@sissa.it">sclauzer@sissa.it</a>>:<br>
<br>
><br>
><br>
> dev sharma wrote:<br>
>> Sir, i want to calculate dielectric constant as a function of<br>
>> frequency. I have read the manual And it is written there that<br>
>> Epsilon.x doesn't support the reduction of the k-points grid into the<br>
>> unreducible Brillouin zone, so the previous PW runs must be performed<br>
>> with a uniform k-points grid and all k-points weights must be equal to<br>
>> each other, i.e. in the k-points card the k-points coordinates must be<br>
>> given manually in \emph{crystal} or \emph{alat} or \emph{bohr}, but not<br>
>> with the \emph{automatic} option.<br>
><br>
> In your first mail you were speaking about the automatic keyword as<br>
> if it was an option<br>
> for a k-point list to be supplied to epsilon.x. As you have now<br>
> reported from the manual,<br>
> epsilon.x does not need a k-point grid, since it uses the k-points<br>
> from the underlying<br>
> data produced by the previous pw.x run.<br>
> For a cubic symmetry system, for instance, you can supply manually a<br>
> N x N x N mesh of<br>
> k-points (using crystal option might be the easiest solution, in my<br>
> opinion), which must<br>
> provide a good sampling the full BZ (it is not difficult to produce<br>
> one, see the source<br>
> code of pwtools/kpoints.f or PW/kpoint_grid.f90).<br>
> Be careful and check the code does not reduce the mesh by symmetry<br>
> (which is the default,<br>
> good behaviour of the code, that in this specific case you want to<br>
> avoid). Use the nosym<br>
> option if needed (as written in the manual).<br>
> You can also try to generate the grid with the automatic option of<br>
> K_POINTS after setting<br>
> to true nosym and noinv (see Doc/INPUT_PW.txt), but I'm not sure if<br>
> this always works.<br>
><br>
><br>
> Regards,<br>
><br>
> GS<br>
><br>
><br>
><br>
>> Thanks<br>
>><br>
>> On Mon, Oct 12, 2009 at 12:40 PM, Gabriele Sclauzero <<a href="mailto:sclauzer@sissa.it">sclauzer@sissa.it</a><br>
>> <mailto:<a href="mailto:sclauzer@sissa.it">sclauzer@sissa.it</a>>> wrote:<br>
>><br>
>><br>
>> dev sharma wrote:<br>
>> > hi 2 all,<br>
>> ><br>
>> > I have one question. In epsilon.x, the k points is not automatic<br>
>> > option. Sir, means how to give the K points option i.e. we have<br>
>> to give<br>
>> > only irreducible k points or like for the calculation ='bands' ,<br>
>> we have<br>
>> > give the path (like G{0,0,0}-->X(0.5,0,0)). If we have to give the<br>
>> > irreducible points , how to calculate those points ???? can i do<br>
>> this ,<br>
>> > that run the pw.x with a mesh like 4*4*4 grid and the number of k<br>
>> > points in the scf output are the required k points<br>
>><br>
>> Never used this utility, so maybe my advice is useless: are you sure<br>
>> that epsilon.x does<br>
>> need a k-point grid on input? For what purpose are you using the<br>
>> program? Do you know what<br>
>> it computes? If not, please look at the documentation in<br>
>> Doc/eps_max.tex.<br>
>><br>
>><br>
>> GS<br>
>><br>
>><br>
>> PS: Please always sign your mails with your name and affiliation. Thanks<br>
>><br>
>><br>
>><br>
>> --<br>
>><br>
>><br>
>> o ------------------------------------------------ o<br>
>> | Gabriele Sclauzero, PhD Student |<br>
>> | c/o: SISSA & CNR-INFM Democritos, |<br>
>> | via Beirut 2-4, 34014 Trieste (Italy) |<br>
>> | email: <a href="mailto:sclauzer@sissa.it">sclauzer@sissa.it</a> <mailto:<a href="mailto:sclauzer@sissa.it">sclauzer@sissa.it</a>><br>
>> |<br>
>> | phone: +39 040 3787 511 |<br>
>> | skype: gurlonotturno |<br>
>> o ------------------------------------------------ o<br>
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><br>
> --<br>
><br>
><br>
> o ------------------------------------------------ o<br>
> | Gabriele Sclauzero, PhD Student |<br>
> | c/o: SISSA & CNR-INFM Democritos, |<br>
> | via Beirut 2-4, 34014 Trieste (Italy) |<br>
> | email: <a href="mailto:sclauzer@sissa.it">sclauzer@sissa.it</a> |<br>
> | phone: +39 040 3787 511 |<br>
> | skype: gurlonotturno |<br>
> o ------------------------------------------------ o<br>
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