non-zero temperature in initialization

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8813204602
Posts: 18
Joined: Tue Jun 15, 2021 5:53 pm

non-zero temperature in initialization

Post by 8813204602 » Wed Oct 06, 2021 10:24 pm

Hello,

I want to calculate the GW band structure for a semiconductor material with Yambo. But because of the use of smearing in Quantum espresso calculations (smearing=mp, degauss=0.001),after initialization, a non-zero temperature and a half-metal material are reported at r-setup.

[X]Electronic Temp. [ev K]: 0.2586E-1 300.1
[X]Bosonic Temp. [ev K]: 0.2586E-1 300.1
[X]Finite Temperature mode: yes
[X]El. density [cm-3]: 0.213E+24
[X]States summary : Full Metallic Empty
[X] [spin up] 0001-0017 0018-0075
[X] [dn] 0001-0015 0016-0016 0017-0075

When I set ElecTemp=0 eV in initialization input file, temperature in r-setup remains non-zero and also material remains half-metal.

[X]Electronic Temp. [ev K]: 0.8617E-5 0.1000
[X]Bosonic Temp. [ev K]: 0.00 0.00
[X]Finite Temperature mode: no
[X]El. density [cm-3]: 0.213E+24
[X]States summary : Full Metallic Empty
[X] [spin up] 0001-0017 0018-0075
[X] [dn] 0001-0015 0016-0016 0017-0075

How I can solve these problems of non-zero temperature and half-metal material?

‌Best,
Mitra Helmi
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Mitra Helmi,Ph.D student
Ferdowsi university of Mashhad
Mashhad,Iran

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Daniele Varsano
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Re: non-zero temperature in initialization

Post by Daniele Varsano » Thu Oct 07, 2021 8:03 am

Dear Mitra,

Yambo reads the energies from QE and then it recalculates the occupation numbers.
If a metallic situation is found a temperature of 300K is considered.

If the system should be semiconductor, you can try to run a QE calculation with fixed occupations, if it converges this should fix your problem.

Best,
Daniele
Dr. Daniele Varsano
S3-CNR Institute of Nanoscience and MaX Center, Italy
MaX - Materials design at the Exascale
http://www.nano.cnr.it
http://www.max-centre.eu/

8813204602
Posts: 18
Joined: Tue Jun 15, 2021 5:53 pm

Re: non-zero temperature in initialization

Post by 8813204602 » Fri Oct 08, 2021 5:12 pm

Dear Daniele

Despite the considaration "occupation=fixed" in the nscf calculation, problems in the r-setup created by Yambo have not been resolved yet.
1) Although smearing is not considered in the nscf calculation,why is the Electronic temperature reported to be 0.1K instead of 0K?
Even setting ElecTemp=0 in the initallization input file does not solve this problem.
2) Why is the partial occupation of band 17 seen in the state K [1] spin up while this problem does not exist in scf and nscf outputs. For this reason, Yambo considers a half-metal system.
When I change the occTresh in the initalization input file from 0.1E-4 to 0.1E-2, there is still this partial occupation, but Yambo considers the system semiconductor this time. If I continue the rest of the calculations using this input (semiconductor system despite partial occupation of band 17), will the results of the obtained band structure be acceptable?

r-setups and QE input and output files are attached.

Best,
Mitra Helmi
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Mitra Helmi,Ph.D student
Ferdowsi university of Mashhad
Mashhad,Iran

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Daniele Varsano
Posts: 3076
Joined: Tue Mar 17, 2009 2:23 pm
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Re: non-zero temperature in initialization

Post by Daniele Varsano » Fri Oct 08, 2021 5:24 pm

Dear Mitra,
When I change the occTresh in the initalization input file from 0.1E-4 to 0.1E-2, there is still this partial occupation, but Yambo considers the system semiconductor this time. If I continue the rest of the calculations using this input (semiconductor system despite partial occupation of band 17), will the results of the obtained band structure be acceptable?,
This seems to me to be ok, I could not spot the partial occupation in the report. It is seen as a semiconductor and at a first glance spin up and spin dn calculation seems to be the same as found by QE. Anyway, I did not look at all the k points carefully. I suggest you to have a deep look comparing the nscf output and the yambo report (you need just to shift the energies by the Fermi level reported in the r_setup.

If the two electronics structures are the same you can go on with the calculations.

Best,
Daniele
Dr. Daniele Varsano
S3-CNR Institute of Nanoscience and MaX Center, Italy
MaX - Materials design at the Exascale
http://www.nano.cnr.it
http://www.max-centre.eu/

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