[Wien] Questions about imposing external magnetic field on no-magnetic system

[Gavin Abo]

I looked at the Landau quantization Wikipedia entry [1]. However, it was 
not clear to me whether this was needed to describe a system with moving 
spin (e.g., oscillating spins).

If so, I think the answer to your question it that your not missing 
anything and WIEN2k does not have an external magnetic field 
implementation for Landau quantization.

In Chapter 10 Landau Quantization on page 182 of the book titled 
"Quantum Hall Effects: Recent Theoretical and Experimental Developments" 
by Zyun F. Ezawa, it mentions that spinless theory is frequently 
considered when the spin degree of freedom can be ignored, such that a 
spin frozen system becomes a good approximation under the condition that 
the Zeeman energy is large.

Previously, I didn't understand Dr. Novak's reference to the frozen spin 
method [2], but it seems now that might be why he mentioned it.

The NMR slides [3,4] do show B_ext in the H_NMR equation, but I don't 
see it described in which input file it is to be included (or if just 
part of a result in an output file).  There is the external magnetic 
field value that can be entered in case.inorb [5].  Perhaps, the NMR 
program also uses that too.

Of note, it was estimated before that a Bext value of a least 1728 T may 
be needed to see any noticeable effect in the plots (if the default 
autoscale-like settings are used) [6].

[1] https://en.wikipedia.org/wiki/Landau_quantization
[2] 
http://www.mail-archive.com/wien@zeus.theochem.tuwien.ac.at/msg01508.html
[3] http://susi.theochem.tuwien.ac.at/events/ws2015/rolask_nmr.pdf
[4] 
http://susi.theochem.tuwien.ac.at/reg_user/textbooks/WIEN2k_lecture-notes_2013/nmr-chemical-shift.pdf
[5] 
http://www.mail-archive.com/wien@zeus.theochem.tuwien.ac.at/msg12904.html
[6] 
https://www.mail-archive.com/wien@zeus.theochem.tuwien.ac.at/msg11093.html

On 7/15/2017 4:56 AM, Karel Vyborny wrote:
> Interesting, I didn't know that WIEN2k can figure out what "band 
> structure with B>0" is... I thought there ought to be some Landau 
> quantisation which is hard to do except for idealised systems. Am I 
> missing something here?
>
> KV
>
>
> --- x ---
> dr. Karel Vyborny
> Fyzikalni ustav AV CR, v.v.i.
> Cukrovarnicka 10
> Praha 6, CZ-16253
> tel: +420220318459
>
>
> On Sat, 15 Jul 2017, Peng Bingrui wrote:
>
>> Dear professor Blaha
>>
>> Thank you very much for your suggestions. However, I'm still kind of
>> confused, because my purpose is to see the change of band structure 
>> under
>> external magnetic field, and l'm wondering whether NMR calculation 
>> can do
>> this ? I'm sorry for my limited knowledge as an undergraduate student.
>>
>> Sincerely yours,
>> Bingrui Peng
>> from the Department of Physics, Nanjing University, China
>>
>> ____________________________________________________________________________ 
>>
>> From: Wien <wien-bounces at zeus.theochem.tuwien.ac.at> on behalf of pieper
>> <pieper at ifp.tuwien.ac.at>
>> Sent: Wednesday, July 12, 2017 1:15:41 AM
>> To: A Mailing list for WIEN2k users
>> Subject: Re: [Wien] Questions about imposing external magnetic field on
>> no-magnetic system
>> In case no one has answered this up to now:
>>
>> ad 1) The procedure itself is ok. You might want switch on SO first and
>> converge that without the orbital potential to establish a zero-field
>> base line. Remember to put in LARGE fields - your off-the-shelf lab
>> field of 10 T will not show up at any energy precision you can achieve.
>> Estimate the energy of 1 mu_B in 10 T field in Ry units to see that.
>>
>> Note that your not-so-recent version of Wien2k is not the best for the
>> task. The latest version is 17.1. With 16.1 came the NMR package which
>> should be much better suited to calculate the effects of a magnetic
>> field.
>>
>> ad 2) If you apply a magnetic field experimentally in the lab you do it
>> at all atoms. I suppose you want to model that situation. imho it makes
>> little sense to exempt one or two of your atoms from the field.
>>
>> Good luck
>>
>> ---
>> Dr. Martin Pieper
>> Karl-Franzens University
>> Institute of Physics
>> Universitätsplatz 5
>> A-8010 Graz
>> Austria
>> Tel.: +43-(0)316-380-8564
>>
>>
>> Am 10.07.2017 12:20, schrieb Peng Bingrui:
>> > Dear professor Blaha and WIEN2K users
>> >
>> > I'm running WIEN2K of 14 version on Linux system. I'm going to impose
>> > external magnetic field on LaPtBi, a no-magnetic material. The
>> > procedure that I'm going to use is :
>> >
>> > 1、Do a no-SO calculation : runsp_c_lapw.
>> >
>> > 2、Do a SO calculation : runsp_c_lapw -so -orb, while including
>> > external magnetic field as orbital potential in the same time.
>> >
>> > My questions are:
>> >
>> > 1、Whether this procedure is OK ? If it is not OK, what is the right
>> > one ?
>> >
>> > 2、Which atoms and which orbitals should I treat with orbital
>> > potential ? The electron configurations of these 3 atoms are: La (5d1
>> > 6s2) ;  Pt  (4f14 5d9 6s1); Bi (4f14 5d10 6s2 6p3).
>> >
>> > Thanks very much for your attention.
>> >
>> > Sincerely yours,
>> >
>> > Bingrui Peng
>> >
>> > from the Department of Physics, Nanjing University, China
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