[DFTB-Plus-User] about DFTB3 on DFTB+ Ver.1.2

[Bálint Aradi]

Dear Prof. Tokiwa,

> In Manual PDF, page 20, for DFTB3 calcultions, set the "ThirdOrder" to
> "YES", and Hubbard Derivs,
> as follows,
> 
> ------------------------------
> HubbardDerivs Derivatives of the Hubbard U for the 3rd order
> correction (on-site or full). For
> every element the appropriate parameter (in atomic units) must be specified:
> Hamiltonian = DFTB {
> :
> ThirdOrder = Yes
> HubbardDerivs {
> O = -0.14
> H = -0.07
> }
> :
> }
> -------------------------------
> 
> However, in original paper (Ref 10 in manual), M. Gaus, Q. Cui, and M.
> Elstner. DFTB3: Extension of the Self-Consistent-Charge Density-
> Functional Tight-Binding Method (SCC-DFTB). J. of Chem. Theory
> Comput., 7:931–948,2011,
> Table 2 shows the different values for Derivatives of the Hubbard U
> for Oxygen & Hydrogen, U_O, & U_H.

 The Hubbard derivatives given in the manual are just examples. Since
they are fitted (!) values in the reference (instead of using the ab
initio atomic derivatives), there are no "global valid" values. If you
would like to reproduce the values given in the paper, please use the
constants given there.

 Best regards,

  Bálint

Ps. Please send any queries about DFTB+ to the DFTB-Plus-User mailing
list, so that everyone can profit from the conversation. Therefore, I
cc'd also this answer to the list.

-- 
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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