[Pw_forum] calculating the stress tensor

[Scandolo Sandro]

A number of useful formulae can be found in Paolo Focher's thesis (1994)
(dowloadable from http://www.sissa.it/cm/phd.php ), as well as in a
subsequent publication:

Paolo Focher and Guido L. Chiarotti
Ab-initio Molecular Dynamics simulations of structural phase transitions
in ``Progress in Computational Physics of Matter'', eds. L. Reatto and F.
Manghi, p. 1-42, World Scientific, Singapore, (1995).

(I can fax you the relevant pages of the latter when I'm back to Trieste,
late August).

Best regards,
Sandro


> Hi,
>
> I and another post-doc are working on implementing a non-local
> functional into PWSCF. It is of the general form:
> E_xc[n(r)] = \int dr dr' n(r) phi(r,r') n(r')
>
> where n(r) and phi(r,r') are the charge density and a kernel,
> respectively.
>
> Forces require calculating V_xc which is analytically complicated, but
> has already been done. The next quantity that we want to compute is
> the stress tensor.
>
> Does any happen to have any notes on calculating the stress tensor in
> a PW basis set?
>
> I looked at the original paper on calculating the stress:
>
> O. H. Nielsen and R. M. Martin, Phys. Rev. Lett. 50, 697 (1983).
>
> Eqn. 3 contains the V_xc (mu_xc in their notation) and it also
> contains epsilon_xc which is the exchange-correlation energy per
> particle which cannot be easily written down in a closed analytic form
> for a non-local functional (I think). Otherwise, I don't see any
> higher derivatives of E_xc in the the expression for the stress.
>
> Does anyone have any useful references?
>
> Thanks,
> --
> Nichols A. Romero, Ph.D.
> 1613 Denise Dr. Apt. D
> Forest Hill, MD 21050
> 443-567-8328 (C)
> 410-306-0709 (O)
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[Pw_forum] Where to find old format pseudopotential files?

[José Rui Faustino de Sousa]

Hi!

Where to find old format pseudopotential files?

Some documentation would be nice too... Corrections to

 would be very welcome.

I have tried the PWscf website, under older version downloads the links
are there, but all the links (at least all that I have tried) to
www.sissa.it seem to be dead.

Versions prior to 1.2.* seem to be unavailable too.

Just as a suggestion it would be nice if there was ftp access to the
pseudopotential files or a compressed file containing the lot.

Thank you very much.

Best regards
Jos? Rui

[Pw_forum] Plot |psi|^2 for an arbitary k point

[Andrea Dal Corso]

On Wed, 2006-07-12 at 12:49 -0700, Tianshu Li wrote:
> Dear PWSCF users and developers:
> 
> In running post-processing pp.x, I got an error message  "from 
> local_dos : error # 1
>  k must be zero" when calculating |psi|^2 for a non-zero K point. 
> I've searched the code "local_dos.F90" and find that the non-zero K 
> point does not seem to be allowed. Since there is a "kpoint" keyword in 
> the input list, I just wonder if the non-zero K point wavefunction 
> visualization has not been implemented yet. Thanks
> 
You are using lsign=.true.. This option is implemented only at the
gamma point. 


Andrea


> Tianshu Li
> 
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-- 
Andrea Dal CorsoTel. 0039-040-3787428
SISSA, Via Beirut 2/4   Fax. 0039-040-3787528
34014 Trieste (Italy)   e-mail: dalcorso at sissa.it