[Wien] Different Rmt's for atoms of one type
Maxim Rakitin
rms85 at physics.susu.ac.ru
Thu Apr 21 17:18:09 CEST 2011
Thank you Laurence and Evgenia,
Laurence, do you mean x_lapw script which attached to 2 emails in the
mailing list?
1) [Wien] severe bug in x_lapw by Peter Blaha on 22.06.2010 2:03.
2) Re: [Wien] LAPW2 crashed in parallel mode by Peter Blaha on
01.07.2010 16:09.
Thanks a lot for your help.
Maxim
21.04.2011 19:57, Евгения Каблиман пишет:
> Maxim, perhaps, you are interesting in calculation of the formation
> energies.
> And therefore, I am personally not sure, how is then better (and
> correct) to estimate this value when Fe atoms have different RMT's in
> one supercell.
> As Laurence very well explained, when "you use different RMTs for the
> Fe in effect you make them different".
>
> 2011/4/21 Laurence Marks <L-marks at northwestern.edu
> <mailto:L-marks at northwestern.edu>>
>
> An approximate explanation, but first a caveat: dealing with small
> RMT's in Wien2k is not completely trivial.
>
> In Wien2k you have two different basis sets, a radial grid + orbitals
> inside the RMT, plane waves outside. If you use different RMTs for the
> Fe in effect you make them different. For instance, try setting up a
> Fe cell with two different RMTs (i.e. a supercell), converge it then
> do aim. You will find that there has been a small charge transfer
> between the Fe's, which will go to zero as you increase RKMAX.
>
> For your problem, I would go beyond setrmt (which is OK, but not
> always optimal) and use a smaller RMT for the C (maybe 1.3) and
> increase that for the Fe. You will have to do this by hand. Be careful
> about going too small with the C as if you do you will lose core
> charge (although .lcore helps); you also need to be careful about
> losing core electrons from the Fe. In both cases look in case.outputm
> to see how far the core integrals are from integers. Scale RKMAX so
> RKMAX/min(RMT) is roughly the same (e.g. 3.5), although you need to
> add a bit when you decrease the RMTs. Probably something like 5-6
> should be good for your problem.
>
> How to chose the "right" RMTs? I don't have any great wisdom, others
> might have. I tend to use RMTCheck (look in the mailing list, or I can
> ask Peter to add it to the contributed software) and check that the
> step in the gradients at the RMT for the different atoms are
> comparable. In most cases this gives results similar to setrmt. In
> principle you can also do calculations for different values with
> RKMAX/min(RMT) fixed and look for the minimum energy -- the few times
> I've done this the results are about the same. Another method would be
> to try and balance the charge lost in the core integrals, which gives
> a similar result.
>
> 2011/4/21 Maxim Rakitin <rms85 at physics.susu.ac.ru
> <mailto:rms85 at physics.susu.ac.ru>>:
> > Thank you Evgenia,
> >
> > I've already seen that link, but I'd like to get information why
> it is not
> > possible from physical point of view.
> >
> > Maxim
> >
> > 21.04.2011 16:53, Евгения Каблиман пишет:
> >
> > Dear Maxim,
> >
> > identical elements should have identical RMT's.
> > This link might help you
> http://www.wien2k.at/reg_user/faq/rmt.html .
> >
> > 2011/4/21 Maxim Rakitin <rms85 at physics.susu.ac.ru
> <mailto:rms85 at physics.susu.ac.ru>>
> >>
> >> Dear WIEN2k community,
> >>
> >> Is it correct to perform calculations with different Rmt radii
> for atoms
> >> of one type, e.g. Fe?
> >>
> >> I need to calculate total energy of a systems containing one
> interstitial
> >> carbon atom in bcc iron matrix. Carbon has quite large
> MT-radius comparing
> >> with H atom, so StructGen sets Rmt(Fe) to 1.59 a.u. and Rmt(C)
> to 1.41 a.u.
> >> for lattice constant 5.394 a.u. In some papers (C. Domain et
> al., PRB 69,
> >> 144112 (2004)) Rmt(C) is even large than I got (~1.6 a.u.) and
> Rmt(Fe) is
> >> also much larger (~2.4 a.u.). But if I use the radii from the
> article,
> >> WIEN2k doesn't allow me to perform further procedures - nn gives me
> >> information about overlapping spheres.
> >>
> >> Can I use Rmt(Fe)=2.4 a.u. in all volume of my supercell except
> of the
> >> nearest iron atoms?
> >>
> >> Thanks in advance for your answers.
> >>
> >> --
> >> Best regards,
> >> Maxim Rakitin
> >> South Ural State University
> >> Chelyabinsk, Russia
> >> email: rms85 at physics.susu.ac.ru <mailto:rms85 at physics.susu.ac.ru>
> >> web: http://www.susu.ac.ru
> >>
> >> _______________________________________________
> >> Wien mailing list
> >> Wien at zeus.theochem.tuwien.ac.at
> <mailto:Wien at zeus.theochem.tuwien.ac.at>
> >> http://zeus.theochem.tuwien.ac.at/mailman/listinfo/wien
> >
> >
> >
> > --
> > Evgeniya Kabliman.
> > Insitute of Materials Chemistry Vienna University of
> Technology
> > Getreidemarkt 9/165-TC, A-1060 Vienna, Austria
> > Tel: +43 1 58801 15674 Fax: +43 1 58801 15698
> > evgeniya at theochem.tuwien.ac.at
> <mailto:evgeniya at theochem.tuwien.ac.at> http://www.imc.tuwien.ac.at
> >
> > _______________________________________________
> > Wien mailing list
> > Wien at zeus.theochem.tuwien.ac.at
> <mailto:Wien at zeus.theochem.tuwien.ac.at>
> > http://zeus.theochem.tuwien.ac.at/mailman/listinfo/wien
> >
> > _______________________________________________
> > Wien mailing list
> > Wien at zeus.theochem.tuwien.ac.at
> <mailto:Wien at zeus.theochem.tuwien.ac.at>
> > http://zeus.theochem.tuwien.ac.at/mailman/listinfo/wien
> >
> >
>
>
>
> --
> Laurence Marks
> Department of Materials Science and Engineering
> MSE Rm 2036 Cook Hall
> 2220 N Campus Drive
> Northwestern University
> Evanston, IL 60208, USA
> Tel: (847) 491-3996 Fax: (847) 491-7820
> email: L-marks at northwestern dot edu
> Web: www.numis.northwestern.edu <http://www.numis.northwestern.edu>
> Chair, Commission on Electron Crystallography of IUCR
> www.numis.northwestern.edu/ <http://www.numis.northwestern.edu/>
> Research is to see what everybody else has seen, and to think what
> nobody else has thought
> Albert Szent-Gyorgi
> _______________________________________________
> Wien mailing list
> Wien at zeus.theochem.tuwien.ac.at
> <mailto:Wien at zeus.theochem.tuwien.ac.at>
> http://zeus.theochem.tuwien.ac.at/mailman/listinfo/wien
>
>
>
>
> --
> Evgeniya Kabliman.
> Insitute of Materials Chemistry Vienna University of Technology
> Getreidemarkt 9/165-TC, A-1060 Vienna, Austria
> Tel: +43 1 58801 15674 Fax: +43 1 58801 15698
> evgeniya at theochem.tuwien.ac.at <mailto:evgeniya at theochem.tuwien.ac.at>
> http://www.imc.tuwien.ac.at
>
>
> _______________________________________________
> Wien mailing list
> Wien at zeus.theochem.tuwien.ac.at
> http://zeus.theochem.tuwien.ac.at/mailman/listinfo/wien
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://zeus.theochem.tuwien.ac.at/pipermail/wien/attachments/20110421/1303d4b4/attachment.htm>
More information about the Wien
mailing list