[Pw_forum] 2nd and 3rd energy derivatives using DFPT?

[Sabry Gad Al Hak Moustafa]

Thanks Stefano;

But, what do you mean by "some"? I am interested specifically in Fe at high
pressure, so, can QE do 3rd derivative for that?

Here

http://www.quantum-espresso.org/wp-content/uploads/Doc/ph_user_guide.pdf

it says

"D3/d3.x: calculates anharmonic phonon lifetimes (third-order derivatives
of the energy), using data produced by pw.x and ph.x (USPP and PAW not
supported)."

So, it looks like it is NCPP.

Thanks;
Sabry



==================================================
Sabry G. Moustafa, Ph.D.
Department of Chemical and Biological Engineering
511 Furnas Hall
University at Buffalo, The State University of New York
Buffalo, NY 14260-4200
716-645-1186 (office)
716-239-8543 (cell)
E-mail: sabrygad at buffalo.edu <kofke at buffalo.edu>

On Wed, Apr 20, 2016 at 12:28 AM, stefano de gironcoli <degironc at sissa.it>
wrote:

> the phonon code evaluates second order derivatives (dynamical matrices).
> this is available for NCPP, USPP and PAW
>
> the D3 code computes some of the third order derivatives.
> it is working for NCPP only as far as I remember.
>
> forth order derivatives are not computed.
>
> stefano
>
>
> On 20/04/2016 06:34, Sabry Gad Al Hak Moustafa wrote:
>
> Hi;
>
> Was wondering if QE can compute 2nd, 3rd and 4th energy derivatives in the
> DFPT framework? If so, is available in PAW, or just PPs?
>
> Thanks;
> Sabry
>
>
>
> ==================================================
> Sabry G. Moustafa, Ph.D.
> Department of Chemical and Biological Engineering
> 511 Furnas Hall
> University at Buffalo, The State University of New York
> Buffalo, NY 14260-4200
> 716-645-1186 (office)
> 716-239-8543 (cell)
> E-mail: <kofke at buffalo.edu>sabrygad at buffalo.edu
>
>
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