[Pw_forum] How to create a new pseudo potential with virtual.x?

[GAO Zhe]

Dear Yuewen:
I'd like to quote a paragraph from L. Vitos' book "Computational quantum mechanics for materials engineers - the EMTO method and applications" at the beginning of page 9:
"This simple model (VCA method) suffers from numerous weaknesses, e.g., it is unable to describe correctly the bond proportion and volume effects, and its application has been limited to alloys with nearly identical chemical species."
So, it is difficult to "exam" whether your mixed potential works well. You may just do some works and compare your results with other persons.
If you wanna use VCA to calculate the energies of alloys, I think Prof. S. de Gironcoli's PRL papers and his Ph.D dissertation are the best.


--
GAO Zhe
CMC Lab, Materials Science & Engineering Department,
Seoul National University, South Korea
 

At 2012-08-02 11:02:00,"Yue-Wen Fang" <yuewen.fang at gmail.com> wrote:
Dear Axel,


    Based on your reply, I chose two similar Pseudo Potentials namely N.pbe-van-bm.UPF and O.pbe-van-bm.UPF and have succeeded in generating a new mixed PP. But, how to confirm the pp's quality? What tests about PP I should make?
    Thank you very much!


Y. -W. Fang


2012/8/1 Axel Kohlmeyer <akohlmey at gmail.com>

On Wed, Aug 1, 2012 at 4:21 AM, Yue-Wen Fang <yuewen.fang at gmail.com> wrote:
> Dear all,
>
>    I want to create a new pesudo potential with virtual.x, but error occurs.
> It shows  different nqf are not implemented,  but i don't know to handle
> this problem and I am also puzzled by the words such as nqf and nqls in the
> file virtual.f90 which locate at ~/espresso/upftools.


nqf obviously refers to the number of Q-functions. please check
out the derivation of ultra-soft pseudopotentials for details.


>    If it is convenient for you, pls give me some advice to curb the problem.


for creating useful "mixed" pseudopotentials with virtual.x,
the two original potential files have to be (technically) as
similar as possible. in many cases it unfortunately means,
that you have to (re-)create the two potentials yourself
based on the provided data (with a few tweaks here and
there) to make certain, they are compatible.

axel.


>    Thank you.
>
> Regards
> Y.-W. Fang
>
>   The details are showed below:
>    console  ~/Examples/pwscf/Ding0731/test1/virtual 09:56:41 >virtual.x
>
>  Generate the UPF pseudopotential for a virtual atom
>  combining two pseudopootentials in UPF format
>
>   Input PP file #  1 in UPF format > F.pbe-n-van.UPF
>   IOS=            0           1           4
>   Reading pseudopotential file in UPF format...
>  ikk2         525         525         525         525         525
> 525
>            0           0           0           0           0           0
>            0           0           0           0
>   ...done
>
>   Input PP file #  2 in UPF format > O.pbe-van_ak.UPF
>   IOS=            0           2           4
>   Reading pseudopotential file in UPF format...
>  ikk2         525         525         525         525         525
> 525
>            0           0         507         507         507         507
>            0           0           0           0
>   ...done
>
>  New Pseudo = x F.pbe-n-van.UPF + (1-x) O.pbe-van_ak.UPF
>  mixing parameter x [0<x<1] = 0.4
>   pseudopotentials have different mesh
>          799         737
>   0.000000000000000E+000  0.000000000000000E+000
>    206.066269763000        81.0552407574000
>   pseudopotentials have different mesh
>  INTERPOLATE = T
>  interpolate rho_atc
>   done
>   interpolate vloc0
>   interpolate betar
>   interpolate betar
>   interpolate betar
>   interpolate betar
>
>
> %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
>      from Virtual : error #         1
>      different nqf are not implemented (yet)
>  %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
> %%%%%%%
>
>      stopping ...
> Fatal error; unknown error handler
> May be MPI call before MPI_INIT.  Error message is MPI_COMM_RANK and code is
> 197
> Fatal error; unknown error handler
> May be MPI call before MPI_INIT.  Error message is MPI_ABORT and code is 197
> forrtl: severe (174): SIGSEGV, segmentation fault occurred
> Image              PC                Routine            Line        Source
> virtual.x          000000000053C9DD  Unknown               Unknown  Unknown
> virtual.x          000000000040FC51  errore_                    94
> error_handler.f90
> virtual.x          000000000040BF61  compute_virtual_          312
> virtual.f90
> virtual.x          00000000004050F4  MAIN__                    107
> virtual.f90
> virtual.x          0000000000404C6A  Unknown               Unknown  Unknown
> libc.so.6          0000003606A1C4BB  Unknown               Unknown  Unknown
> virtual.x          0000000000404BAA  Unknown               Unknown  Unkn
>

> _______________________________________________
> Pw_forum mailing list
> Pw_forum at pwscf.org
> http://www.democritos.it/mailman/listinfo/pw_forum
>



--
Dr. Axel Kohlmeyer  akohlmey at gmail.com  http://goo.gl/1wk0
International Centre for Theoretical Physics, Trieste. Italy.
_______________________________________________
Pw_forum mailing list
Pw_forum at pwscf.org
http://www.democritos.it/mailman/listinfo/pw_forum


-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.quantum-espresso.org/pipermail/users/attachments/20120804/96c46362/attachment.html>