[Pw_forum] XSpectra hybrid functional

Matteo Calandra matteo.calandra at impmc.jussieu.fr
Wed Oct 24 14:06:05 CEST 2012

Le 24/10/12 12:00, pw_forum-request at pwscf.org a écrit :

>It is possible indeed, in the sense that the XSPECTRA code does not stop complaining if you perform
>the calculation starting from an electronic density calculated by using hybrid functionals (or
>DFT+U). But the XSPECTRA code has not a calculation kernel including EXX terms, as just pointed out
>by Matteo Calandra. Thus:

Not exactly. In the case of DFT+U, the lanczos is performed, as it must 
be, with the
U term included in the hamiltonian. So the Hamiltonian H used in 
XSpectra to perform
H|psi> is the same used to generate the charge density.
This is of course what must be done. So everything is consistent with DFT+U.

If you take the charge density calculated with hybrids and calculate the 
without hybrid I do not think that the result is very meaningful...


* * * *
Matteo Calandra, Directeur de Recherche (DR2)
Institut de Minéralogie et de Physique des Milieux Condensés de Paris
Université Pierre et Marie Curie, tour 23, 3eme etage, case 115
4 Place Jussieu, 75252 Paris Cedex 05 France
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