[Pw_forum] A Cutting-edge Question !!!

[Matteo Cococcioni]

Dear Ashkan,

I'm not sure I understand your question completely, but will attempt an
answer.

First thing to keep in mind is that QE (as any other DFT code) works with
the Kohn-Sham single particle Hamiltonian (is that what you are looking
for?), whose eigenstates are the ones that allow you to construct the
ground state charge density of a system and to evaluate its total energy.
Due to the Bloch theorem (i.e. to the translational invariance of
crystalline solids) this Hamiltonian is block-diagonal on the k-points
(crystal momentum of electrons). Also, QE uses an expansion of Kohn-Sham
wavefunctions on a plane-wave basis set. So, each of these blocks of the
Hamiltonian is npw x npw where npw is the number of plane-waves used in the
expansion of the wavefunctions of that specific k-point. QE performs an
iterative diagonalization of each block that is involves computing the
action of the Hamiltonian onto the current wavefunction H |psi>. This is
done in a routine called h_psi which is the driver to compute various parts
of the Hamiltonian and to operate it on the wavefunction. So I guess you
can look inside that routine in order to find what you need.

Best regards,

Matteo

On Sun, Nov 13, 2016 at 11:24 PM, ashkan shekaari <shekaari at gmail.com>
wrote:

> Dear experts,
>
> How, could one derive the Hamiltonian of a given system resulting in
> energy eigenvalues (band structure) *through the modules or subroutines*
> included in Q. E. integrated suite?
>
> Is there anyway for this end?
>
> For example, if I provide an input scf file, how could I figure out what
> Hamiltonian will be used in my calculations?
>
> How could I make a change in the Hamiltonian of a system by manipulating
> subroutines (not the input file)?
>
>
> *--*
> *Regards,*
> *Ashkan Shekaari*
> *Plasma Physics Research Center*
> *Science and Research Branch*
> *I A U, 14778-93855 Tehran, Iran.*
>
> _______________________________________________
> Pw_forum mailing list
> Pw_forum at pwscf.org
> http://pwscf.org/mailman/listinfo/pw_forum
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.quantum-espresso.org/pipermail/users/attachments/20161114/acd56248/attachment.html>