[Pw_forum] Request about the "real" total energy

[steve ndengué]

Dear all,

We have an enquiry about some results appearing in the output file of the pw.x run.

We
 are trying to perform computations on isolated atoms to try to get a 
significance of the results given by the code. We have to recall that we
 are new users of QE. And as far as we know it is not too much indicated
 for such kind of computations but it is rather a first try to get some 
understanding on the "behaviour" of the code.

So the problem is 
that when performing the computations on He for example we obtain the 
correct ground state energy up to the Hartree-Fock limit. But when 
applied to other atoms (Li, Na, Be, C, ...) the value obtained do not 
correspond at all to the known value.

We thus have 2
 questions:

1- Why is it that the level of refinement obtained is
 the Hartree-Fock limit; we may have expected a better accuracy? Is it 
linked to the use of pseudo-potentials?
2- What can we do to recover the correct (up to the Hartree-Fock limit at least) total energy for the other atoms? 
 
Sincerely Yours,
On behalf of the 
Groupe  de Structure et Dynamique des Atomes et Molecules
Laboratoire de Physique Fondamentale
Département de Physique
Université de Douala.

Steve.


      
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