[Pw_forum] what origin of difference in obtained energy from Dmol3 and ESPRESSO?

[Ari P Seitsonen]

Dear Ehsan targholi,

   In general no: You should have exactly the same pseudo potential for 
both. Then there could still remain other potential, numerical sources for 
differences (treatment of the evaluation of exchange-correlation, basis 
set, ...), but those would be much smaller.

   Thus, most likely there is no way to compare directly, unless you know 
how to generate specific pseudo potentials for Dmol3 (or even more 
miraculously, that it would read the pseudo potentials in the UPF format). 
Another note is maybe in place here, the localised basis sets usually 
depend on the pseudo potential used (if any, namely in all-electron 
treatment the potential is and remains -Z/r); in the case of plane wave 
basis it is sufficient to change the cut-off energy, in case needed to 
achieve good convergence with respect to the basis set.

     Greetings,

        apsi

-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-
   Ari Paavo Seitsonen / Ari.P.Seitsonen at iki.fi / http://www.iki.fi/~apsi/
   Ecole Normale Supérieure (ENS), Département de Chimie, Paris
   Mobile (F) : +33 789 37 24 25    (CH) : +41 79 71 90 935


On Sun, 28 Jun 2015, ehsan targholi wrote:

> thanks a lot for your proper answer. my notion of your answer is that if i
> change the all-electron trearment to pseudo potential treatment in Dmol3, it
> give the same energy with ESPRESSO. is it true?
> 
> 
> best regards
> 
> On Sun, Jun 28, 2015 at 3:28 PM, Ari P Seitsonen <Ari.P.Seitsonen at iki.fi>
> wrote:
>
>       Dear Ehsan targholi,
>
>         Keyword here is "pseudo potential" (QE), versus (probably)
>       all-electron calculation in Dmol3. In practise one is almost
>       always interested in energy differences between different
>       systems but the same approach, and thus total energies never
>       appear there.
>
>           Greetings from Montrouge,
>
>              apsi
> 
> -=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*
>       =-
>         Ari Paavo Seitsonen / Ari.P.Seitsonen at iki.fi /
>       http://www.iki.fi/~apsi/
>         Ecole Normale Supérieure (ENS), Département de Chimie, Paris
>         Mobile (F) : +33 789 37 24 25    (CH) : +41 79 71 90 935
> 
>
>       On Sun, 28 Jun 2015, ehsan targholi wrote:
>
>             hi to every one
>             Dear all
>             i have a serious problem. when i performed the
>             attached input calculation
>             with ESPRESSO, i gave the total energy equal to
>             -71.43856899 Ry that is very
>             different with output of Dmol3 software that gave
>             the total energy equal to 
>             -210.165297Ha ( -420.330 594 Rydberg [Ry]).
>             the same calculation input has been used for both
>             software.
>             I am quite confused.
> 
>
>             best regard
>             Ehsan targholi
> 
> 
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