[DFTB-Plus-User] Question regarding H data in SK files

[Bálint Aradi]

Dear Reinaldo,

> Formally, there is a reference density, n0, to be used to obtain the
> above terms. Then, a small fluctuation (dn0) that relates the true
> density, n, with n0 is used to develop the SCC terms. Please, correct me
> if I'm wrong.

  That's completely true, the Hss etc. terms are calculated at the
reference density.

> My question is, How are the different Hamiltonian terms obtained? Are
> they self-consistent or not? I understand they do not enter the
> self-consistency within the DFTB model but it is not clear for me if
> tabular data in SK files are obtained from SCF Kohn-Sham like
> calculations of from non-SCF KS ones.

 Calculating an integral like

< phi_A | T + V_A + V_B | phi_B >

is done using phi_A and V_A obtained from self consistent calculations
for atom A. The same for V_B and phi_B. After this is done, we calculate
the integrals with those fixed phis and Vs. So the integrals are not
self consistent diatomic calculations, but diatomic integrals between
self consistent atomic quantities.

 I hope that helps somewhat to clear the issue.

  Best regards,

  Bálint

-- 
Dr. Bálint Aradi
Bremen Center for Computational Materials Science, University of Bremen
http://www.bccms.uni-bremen.de/cms/people/b_aradi/


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