[Wien] Fwd:

huimei liu wwillforever at gmail.com
Tue Nov 25 04:15:28 CET 2014


I'm very sorry to bother your again.
 Two question:
1. For a system with SOC effect, can I get clean spin contribution
by using  lapwdm (alpha and beta), since the the orbital can be hard to
distinguishe from spin with SOC included.  For a system with no SOC, I can
forget the orbital moments since the spin texture <ψ|σ|ψ> can be calculated
using the spin orperater σ alone and  the orbital moments is irrelevant .
2. If I can not get clean spin contribution, I'll have to write down the
wavefunction directily and perform <ψ|σ|ψ> by myself.  In this case, I'm
still confused where I can get the radial wavefunction ul(r,E2,l) file?

2014-11-25 4:08 GMT+08:00 Peter Blaha <pblaha at theochem.tuwien.ac.at>:

> As I said before: lapwdm can do the job.
>
> What I called spin-up/dn partial charges are the products
> alpha*alpha and beta*beta, and their difference is Pz.
>
> The cross-terms, leading to Px and Py are not listed individually, but
> they are calculated in lapwdm, but in the output (scfdmup) summed up
> over all states (and k-points).
>
> This was what I already sent before: if you really want it for every state,
> you need to run 1 k-point (lapw1 -up/dn; lapwso -up; lapw2 -so -up/dn -all
> emin emax;
> lapwdm -up -so
>
> and emin/emax should be set such that only ONE state at the time is
> occupied.
>
> The case.scfdmup file has the info under the label   :SPIN
>
> (but can you really forget the orbital moments ... ??   :ORB )
>
>
> Am 24.11.2014 14:37, schrieb Fecher, Gerhard:
>
>  I guess you are searching for the x and y components of the spin
>> polarisation because usually only the z-component
>> Pz = alpha alpha* - beta beta*
>> is given (alpha, beta being the "up" and "down" components of a 2
>> component spinor, * means conjugate complex)
>> the remaining two components (x and y-component) are
>> Px =  2 Re(alpha beta*)   (Re = real part)
>> Py = -2 Im(alpha beta*)   (Im =imaginary part)
>>
>> it assumed that alpha beta are normalized to alpha alpha* + beta beta* =
>> 1, otherwise you need to divide for normalization.
>>
>> For wave functions that arise from a coherent superposition of spinors
>> you should have Px^2 + Py^2 + Pz^2 = P = 1
>> but not for an incoherent superposition of spinors (e.g. two spaghetti
>> are crossing), then P may be lower than 1.
>>
>> if Pz is calculated somewhere in a subroutine, then it should be possible
>> to calculate Px and Py
>>
>> maybe this helps you or Peter to localize the place (subroutine) to look
>> for to answer your request.
>>
>> Problems will appear with the above definition if the "small" coponent of
>> a 4 component Dirac spinor is large compared to the "large component"
>>
>> An old but still very good source about spin polarization is the book of
>> J. Kessler "Polarized Electrons" (1976) from Springer  (may be it is sold
>> out but still available online).
>>
>> Ciao
>> Gerhard
>>
>> DEEP THOUGHT in D. Adams; Hitchhikers Guide to the Galaxy:
>> "I think the problem, to be quite honest with you,
>> is that you have never actually known what the question is."
>>
>> ====================================
>> Dr. Gerhard H. Fecher
>> Institut of Inorganic and Analytical Chemistry
>> Johannes Gutenberg - University
>> 55099 Mainz
>> and
>> Max Planck Institute for Chemical Physics of Solids
>> 01187 Dresden
>> ________________________________________
>> Von: wien-bounces at zeus.theochem.tuwien.ac.at [wien-bounces at zeus.theochem.
>> tuwien.ac.at] im Auftrag von huimei liu [wwillforever at gmail.com]
>> Gesendet: Montag, 24. November 2014 13:18
>> An: A Mailing list for WIEN2k users
>> Betreff: Re: [Wien] Fwd:
>>
>> If so, where can I get ul(r,E2,l) file?
>> Is there any output files that can directily tell me <ψ|σ|ψ> ?
>> Thank you very much!
>>
>> 2014-11-24 17:20 GMT+08:00 Peter Blaha <pblaha at theochem.tuwien.ac.at<
>> mailto:pblaha at theochem.tuwien.ac.at>>:
>> The error depends on how large the Blm component is. Usually it should be
>> SMALL and therefore for an qualitative analysis negligible.
>>
>> However, there could be local orbitals and "Clm"s in certain cases, which
>> could lead to errors of 100 %.
>>
>>
>> On 11/24/2014 10:00 AM, huimei liu wrote:
>>
>> Dear Wien2k designers and users:
>> It seems I want more than  the spin-up and dn contribution for a state.
>> I 'd like to draw the spin texture.
>>
>> I want to calculate the spin direction for a state (k-point +
>> band-index)  using the formalism <ψ|σ|ψ> to evaluate the x,y and z
>> component of spin. Since I can get the Alm and Blm of the Wave function
>> :ψ can be written as the sum of [Alm*ul(r)+Blm*ul'(r)]Ylm. Here is the
>> question, if I use Alm only to calculate  <ψ|σ|ψ>, can I get the  close
>> answer?  Or can anyone tell me the margin of error of using Alm only
>> compared with using Alm and Blm toghther.
>>
>>
>>
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>>
>> --
>>
>>                                        P.Blaha
>> ------------------------------------------------------------
>> --------------
>> Peter BLAHA, Inst.f. Materials Chemistry, TU Vienna, A-1060 Vienna
>> Phone: +43-1-58801-165300             FAX: +43-1-58801-165982
>> Email: blaha at theochem.tuwien.ac.at<mailto:blaha at theochem.tuwien.ac.at>
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>>
> --
> -----------------------------------------
> Peter Blaha
> Inst. Materials Chemistry, TU Vienna
> Getreidemarkt 9, A-1060 Vienna, Austria
> Tel: +43-1-5880115671
> Fax: +43-1-5880115698
> email: pblaha at theochem.tuwien.ac.at
> -----------------------------------------
>
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