[Wien] Non-self consistent energy (not just W2k)

[Dr. K. C. Bhamu]

VASP (SiGe2N4):
  free energy    TOTEN  =       290.13702589 eV
  free energy    TOTEN  =       -76.80006711 eV
  free energy    TOTEN  =       -97.38095302 eV
  free energy    TOTEN  =       -97.83342560 eV
  free energy    TOTEN  =       -97.84185451 eV
  free energy    TOTEN  =       -97.84222510 eV
  free energy    TOTEN  =       -97.84223081 eV
  free energy    TOTEN  =       -97.84223105 eV
  free energy    TOTEN  =       -97.84223106 eV
  free energy    TOTEN  =       -97.84223106 eV

On Tue, Feb 1, 2022 at 1:46 AM Tran, Fabien <fabien.tran at tuwien.ac.at>
wrote:

> Same with VASP (diamond with PBE):
>   free energy    TOTEN  =        -1.21275660 eV
>   free energy    TOTEN  =       -18.71976229 eV
>   free energy    TOTEN  =       -18.82704051 eV
>   free energy    TOTEN  =       -18.82722009 eV
>   free energy    TOTEN  =       -18.82722027 eV
>   free energy    TOTEN  =       -18.34948885 eV
>   free energy    TOTEN  =       -18.18874460 eV
>   free energy    TOTEN  =       -18.19001031 eV
>   free energy    TOTEN  =       -18.19002618 eV
>   free energy    TOTEN  =       -18.19003899 eV
>   free energy    TOTEN  =       -18.19003886 eV
>   free energy    TOTEN  =       -18.19003886 eV
>
> ________________________________________
> From: Wien <wien-bounces at zeus.theochem.tuwien.ac.at> on behalf of Peter
> Blaha <pblaha at theochem.tuwien.ac.at>
> Sent: Monday, January 31, 2022 4:53 PM
> To: wien at zeus.theochem.tuwien.ac.at
> Subject: Re: [Wien] Non-self consistent energy (not just W2k)
>
> In WIEN2k the total energy does not go to a minimum during scf, but even
> more negative values can occur during scf.
>
> It would be interesting to know if this is the same in other codes or not.
>
> grep :ene 5_default.scf
> :ENE  : ********** TOTAL ENERGY IN Ry =       -14900.61390837     <====
> :ENE  : ********** TOTAL ENERGY IN Ry =       -14900.50214748
> :ENE  : ********** TOTAL ENERGY IN Ry =       -14900.50211022
> :ENE  : ********** TOTAL ENERGY IN Ry =       -14900.50200377
> :ENE  : ********** TOTAL ENERGY IN Ry =       -14900.50748913
> :ENE  : ********** TOTAL ENERGY IN Ry =       -14900.51004385
> :ENE  : ********** TOTAL ENERGY IN Ry =       -14900.51010217
> :ENE  : ********** TOTAL ENERGY IN Ry =       -14900.51073277
> :ENE  : ********** TOTAL ENERGY IN Ry =       -14900.51072611
> :ENE  : ********** TOTAL ENERGY IN Ry =       -14900.51066136
> :ENE  : ********** TOTAL ENERGY IN Ry =       -14900.51216359     <====
> :ENE  : ********** TOTAL ENERGY IN Ry =       -14900.51034576
> :ENE  : ********** TOTAL ENERGY IN Ry =       -14900.50887600
> :ENE  : ********** TOTAL ENERGY IN Ry =       -14900.50840575
> :ENE  : ********** TOTAL ENERGY IN Ry =       -14900.50840424
> :ENE  : ********** TOTAL ENERGY IN Ry =       -14900.50840424     <====
>
>
> Am 31.01.2022 um 15:23 schrieb Laurence Marks:
> In Wien2k the total energy is calculated in part from the current density,
> in part from the density of the orbitals that solve the KS equation. As
> such it is not a true variational energy except when the density is
> converged. [1]
>
> For other dft codes (not wavefunction codes [2]), is it the same, e.g.
> Vasp, QE, ab-init? Responses welcome, either via the list of directly.
>
> [1] There are technically ways one could calculate some form of
> variational energy, but it would require extra steps and to my knowledge
> has never looked useful so is not in the code.
> [2] In wavefunction codes where one varies the occupancy the energy is
> typically variational I think.
>
> --
> Professor Laurence Marks
> Department of Materials Science and Engineering
> Northwestern University
> www.numis.northwestern.edu<http://www.numis.northwestern.edu/>
> "Research is to see what everybody else has seen, and to think what nobody
> else has thought" Albert Szent-Györgyi
>
>
>
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>
> --
> -----------------------------------------------------------------------
> Peter Blaha,  Inst. f. Materials Chemistry, TU Vienna, A-1060 Vienna
> Phone: +43-158801165300
> Email: peter.blaha at tuwien.ac.at<mailto:peter.blaha at tuwien.ac.at>
> WWW:   http://www.imc.tuwien.ac.at      WIEN2k: http://www.wien2k.at
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