[Wien] To LO or not to LO ?

[L. D. Marks]

Thanks. For a big calculation LO's seem to be comparatively cheap. I have
noticed that one should not go overboard and too many can make things go
nuts.

On Mon, 15 Nov 2004, Peter Blaha wrote:

> > I seem to have a blind spot when it comes to using LO's. I've noticed that
> > with bulk rutile TiO2 (running LDA) write_in1 is picking up a D LO (GGA
> > does not); Q-d-low is 0.0545 which is just enough. With a reduced TiO2-x
> > calculation run spin-polarized (LDA) the LO is not being picked up in part
> > because the charge is now up/dn partitioned so is less than 0.05, the
> > default cutoff. I could raise -ql in write_in1 for the bulk, or reduce -ql
> > for the reduced TiO2-x calculation; any suggestions as to which is more
> > "correct"?
>
> Using additional LOs should enrich the basis set and thus always be better,
> (unless you get ghostbands because of approximate linear dependencies).
>
> Of course, it might be that you do not gain much (E-tot does not decrease too
> much). Just test it, but judge if the additional effort (5 extra basis functions
> per atom) justify the gain.
>
>
>                                       P.Blaha
> --------------------------------------------------------------------------
> Peter BLAHA, Inst.f. Materials Chemistry, TU Vienna, A-1060 Vienna
> Phone: +43-1-58801-15671             FAX: +43-1-58801-15698
> Email: blaha at theochem.tuwien.ac.at    WWW: http://info.tuwien.ac.at/theochem/
> --------------------------------------------------------------------------
>
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-----------------------------------------------
Laurence Marks
Department of Materials Science and Engineering
MSE Rm 2036 Cook Hall
2225 N Campus Drive
Northwestern University
Evanston, IL 60201, USA
Tel: (847) 491-3996 Fax: (847) 491-7820
mailto:L-marks at northwestern.edu
http://www.numis.northwestern.edu
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