[Wien] Band structure sensitivity to RMT reduction

Oleg Rubel rubelo at mcmaster.ca
Wed Nov 6 18:20:23 CET 2019


Dear All,

thank you for the comments and suggestions. It was a silly mistake on 
our end + rigid instructions in the tutorial I made:

1) The structure referred to as "no RMT reduction" was not 0% reduction 
at all (as Peter guessed). It was initialized with
	init_lapw -b -vxc 13 -rkmax 7 -numk 300
instead of the tutorial recommendation
	init_lapw -b -vxc 13 -red 3 -rkmax 7 -numk 300
leading to R(Ta)=R(As)=2 bohr. There is in fact a lot of interstitial 
space between MT radii and still no core leakage.

2) Because of significantly smaller RMTs compared to the tutorial, the 
Kmax also changed significantly causing a large change in the Fermi 
energy. The resultant Fermi energy becomes 0.917 Ry vs 0.801 Ry in the 
tutorial. Since the band structure is plotted within a narrow energy 
window +/- 1 eV, we saw the adjacent low-energy part of the same band 
structure.

Thank you all for the help once again!

Best regards
Oleg

--
Oleg Rubel (PhD, PEng)
Department of Materials Science and Engineering
McMaster University
JHE 359, 1280 Main Street West, Hamilton, Ontario L8S 4L8, Canada
Email: rubelo at mcmaster.ca
Tel: +1-905-525-9140, ext. 24094
Web: http://olegrubel.mcmaster.ca

On 2019-11-05 14:00, Peter Blaha wrote:
> Dear Oleg,
> 
> I cannot reproduce this.
> 
> Using RMTs of 2.5 /2.38 (this is what setrmt gives without any 
> reduction) I get basically the same band structure as yours with reduction.
> 
> Maybe you did not execute setrmt at all and have RMT=2.0 ??  Then the SO 
> effect would only be taken partly into account.
> 
> 
> 
> Am 05.11.2019 um 18:40 schrieb Oleg Rubel:
>> Thank you for the comments!
>>
>> There is no leakage with any reduction used. The init_lapw runs clean 
>> (no warnings). There are very tiny changes in RMTs when going from 
>> 0.5% to 0% reduction.
>>
>> Best regards
>> Oleg
>>
>>
>> On 11/5/2019 11:43 AM, Laurence Marks wrote:
>>> Remember, SOC is only within the RMTs, see 
>>> http://www.wien2k.at/events/ws2017/notes/Rocquefelte-Relativity-NCM.pdf
>>>
>>> N.B., if the RMTs are too large you may also have leakage. For 
>>> instance, with NiO (for instance) if too large an RMT is used for the 
>>> Ni the O 2p states can leak into the Ni RMT which can lead to 
>>> anomalies with +U or -eece.
>>>
>>> On Tue, Nov 5, 2019 at 10:28 AM Oleg Rubel <rubelo at mcmaster.ca 
>>> <mailto:rubelo at mcmaster.ca>> wrote:
>>>
>>>     Dear Wien2k Community,
>>>
>>>     I compute the band structure of TaAs. The steps are set in the 
>>> tutorial
>>>     file "TaAs topological.pdf" available via the download link 
>>> below. In
>>>     the tutorial, I recommended a 3% RMT reduction even though the
>>>     structural relaxation is not intended. With this settings, it is
>>>     possible to get the band structure (see file "with-SOC.pdf"), 
>>> which is
>>>     very similar to the literature.
>>>
>>>     However, if the RMT redirection is skipped during initialization 
>>> (RMT
>>>     redirection = 0), the band structure transforms drastically (see 
>>> file
>>>     "with-SOC.pdf"). It seems that the value of the gap between 
>>> spheres is
>>>     not important. It is important to have it (even 0.5% is OK).
>>>     Interestingly, the presence of a gap between MT spheres affects the
>>>     band
>>>     structure only when SOC is present. The band structure is _not_
>>>     sensitive to the presence of a gap between MT spheres without SOC 
>>> (see
>>>     file "without-SOC.pdf").
>>>
>>>     As far as I understand, the wave function is continuous in the value
>>>     and
>>>     slope at the interface between MT region and the interstitial (plane
>>>     wave) region. Perhaps, this condition is not fulfilled in the point
>>>     where two MT spheres touch each other? What I do not understand 
>>> is why
>>>     it has such profound consequences only with SOC? Any thought will be
>>>     appreciated.
>>>
>>>     Thank you in advance.
>>>
>>>     Best regards
>>>     Oleg
>>>
>>>     Files download link (avalable for 7 days):
>>> https://urldefense.proofpoint.com/v2/url?u=https-3A__wetransfer.com_downloads_eabd33ab1535992fd1a610b8423aaf9420191105154634_71ff8dc7d5840ed6b1c9703135c1cb8420191105154634_44d984&d=DwICAg&c=yHlS04HhBraes5BQ9ueu5zKhE7rtNXt_d012z2PA6ws&r=U_T4PL6jwANfAy4rnxTj8IUxm818jnvqKFdqWLwmqg0&m=VggiwdRvos4hS2m6aY8z55ptzMRHvrcvRtpXkOVPX1I&s=z2PxBovEK4VE4a2Q1GsDsNZ2Xi2g5f33dhdv63f6TyY&e= 
>>>
>>>
>>>
>>>     --     Oleg Rubel (PhD, PEng)
>>>     Department of Materials Science and Engineering
>>>     McMaster University
>>>     JHE 359, 1280 Main Street West, Hamilton, Ontario L8S 4L8, Canada
>>>     Email: rubelo at mcmaster.ca <mailto:rubelo at mcmaster.ca>
>>>     Tel: +1-905-525-9140, ext. 24094
>>>     Web:
>>> https://urldefense.proofpoint.com/v2/url?u=http-3A__olegrubel.mcmaster.ca&d=DwICAg&c=yHlS04HhBraes5BQ9ueu5zKhE7rtNXt_d012z2PA6ws&r=U_T4PL6jwANfAy4rnxTj8IUxm818jnvqKFdqWLwmqg0&m=VggiwdRvos4hS2m6aY8z55ptzMRHvrcvRtpXkOVPX1I&s=CAxx1qmO-zULEZwepo5VowgIZSez-bLvWebZmAuX4Gs&e= 
>>>
>>>
>>>     _______________________________________________
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>>>
>>>
>>> -- 
>>> Professor Laurence Marks
>>> Department of Materials Science and Engineering
>>> Northwestern University
>>> www.numis.northwestern.edu <http://www.numis.northwestern.edu/>
>>> Corrosion in 4D: www.numis.northwestern.edu/MURI 
>>> <http://www.numis.northwestern.edu/MURI>
>>> Co-Editor, Acta Cryst A
>>> "Research is to see what everybody else has seen, and to think what 
>>> nobody else has thought"
>>> Albert Szent-Gyorgi
>>>
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