[QE-users] syntax of using starting_ns_eigenvalue for two different localized orbitals of the same atom

Fri Aug 12 12:23:55 CEST 2022

Dear Iurii,

Hi.

Thank you for your reply.

I guessed that this new feature in the QE is not complete. However, my needs 
were met.

I highly appreciate the Developers for Easy-Coding the Hubbard feature in 
QE.

Best regards,

Mahmoud

From: Iurii TIMROV <iurii.timrov at epfl.ch>
To: Mahmoud Payami Shabestari <mpayami at aeoi.org.ir>, "Quantum ESPRESSO users 
Forum" <users at lists.quantum-espresso.org>
Date: Fri, 12 Aug 2022 08:11:52 +0000
Subject: Re: [QE-users] syntax of using starting_ns_eigenvalue for two 
different localized orbitals of the same atom

> However, suppose the Hubbard atom is Ce, "[Xe]6s2 4f1 5d1" with two 
localized incomplete orbitals of Ce-4f and Ce-5d. Then how can one specify 
the starting_ns_eigenvalue for both of them with l=3 and l=2?

This is currently not possible to do (not implemented). 
starting_ns_eigenvalue changes only the eigenvalues of the occupation matrix 
corresponding to the first Hubbard channel.

Note that applying +U to two Hubbard channels of the same atomic type is a 
relatively new feature, and hence many things are not supported for this 
case (like the issue mentioned about).

> It seems that the second localized orbital is treated as "background part" 
and accidentally(?!) the eigenvectors of its nod-degenerate eigenvalues are 
set to 1.0 !

The second Hubbard channel can be called "background", but it is nothing but 
just the second channel. The populations of the first and second Hubbard 
channels are initialized in the code (PW/src/init_ns.f90) and I do not 
really understand what is "accidental". If you want to have more precise 
answers, you should be more specific.

HTH

Iurii

--
Dr. Iurii TIMROV
Senior Research Scientist
Theory and Simulation of Materials (THEOS)
Swiss Federal Institute of Technology Lausanne (EPFL)
CH-1015 Lausanne, Switzerland
+41 21 69 34 881
http://people.epfl.ch/265334
From: users <users-bounces at lists.quantum-espresso.org> on behalf of Mahmoud 
Payami Shabestari via users <users at lists.quantum-espresso.org>
Sent: Friday, August 12, 2022 7:48:32 AM
To: Mahmoud Payami Shabestari; Quantum ESPRESSO users Forum
Subject: Re: [QE-users] syntax of using starting_ns_eigenvalue for two 
different localized orbitals of the same atom

It seems that the second localized orbital is treated as "background part" 
and accidentally(?!) the eigenvectors of its nod-degenerate eigenvalues are 
set to 1.0 !

mahmoud

From: "Mahmoud Payami Shabestari" <mpayami at aeoi.org.ir>
To: "Quantum ESPRESSO users Forum" <users at lists.quantum-espresso.org>
Date: Fri, 12 Aug 2022 07:32:05 +0430
Subject: Re: [QE-users] syntax of using starting_ns_eigenvalue for two 
different localized orbitals of the same atom

Dear Stefano,

Hi.
Thank you for your detailed explanation for the Fe case.
However, suppose the Hubbard atom is Ce, "[Xe]6s2 4f1 5d1" with two 
localized incomplete orbitals of Ce-4f and Ce-5d. Then how can one specify 
the starting_ns_eigenvalue for both of them with l=3 and l=2?
Thank you in advance.

Best regards,
mahmoud

From: Stefano de Gironcoli <degironc at sissa.it>
To: Mahmoud Payami Shabestari via users <users at lists.quantum-espresso.org>
Date: Thu, 11 Aug 2022 21:19:56 +0200
Subject: Re: [QE-users] syntax of using starting_ns_eigenvalue for two 
different localized orbitals of the same atom

suppose your Hubbard atom of type 1 is an Fe ( U on 3d orbitals)..., then
starting_ns_eigenvalue(3,1,1)=1.0  overwrites the third eigenvalue of the 
occupations with spin=1 (up) to 1.0
starting_ns_eigenvalue(4,1,1)=0.3 overwrites the forth eigenvalue of the 
occupations with spin=1 (up) to 0.3
starting_ns_eigenvalue(5,2,1)=0.0 overwrites the fifth eigenvalue of the 
occupations with spin=2 (dw) to 0.0
the other elements are left unchanged.
In general at the first iteration the code computes the occupation matrix 
ns, diagonalizes it, overwrites the eigenvalues if required in input and 
then calculates the output ns matrix from the (overwritten) eigenvalue 
decomposition.
if you specify more starting_ns_eigenvalue lines for a given atomic type the 
code will apply all of them independently
stefano
On 11/08/22 21:00, Mahmoud Payami Shabestari via users wrote:
Dear QE-7.1 Developers,

Hi. I would like to use the starting_ns_eigenvalue()=1.0 for two different 
localized orbitals of the same atom. I do not have problem in the HUBBARD 
card, but I do not know how to use starting_ns_eigenvalue()=1.0 for 
different orbital angular momenta of the same atom.
Any comments is highly appreciated.

Best regards,
Mahmoud Payami

---------------------------------------
Mahmoud Payami
NSTRI, AEOI, Tehran, Iran

Email: mpayami at aeoi.org.ir
Phone: +98 (0)21 82066504
--------------------------------------------------------

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