[QE-users] Run error of M06 exchange with libxc 4.3.4

Mon Dec 12 10:30:10 CET 2022

So you start from the scratch of the index notation:
XC-000i-000i-000i-000i-000i-000i
The first slot is for LDA-exchange, the second LDA correlation, the third GGA exchange, then GGA correlation, MGGA exchange and MGGA correlation.
Now, you want to use the MGGA_C_M06 (with no exchange?) which has ID=235, so you put the index here:
XC-000i-000i-000i-000i-000i-235L
The 'L' means that the functional is from Libxc.
If, for example, you want to add en exchange term too, let's say a simple Slater exchange from QE internal library (id=1), then the dft name becomes:
XC-001i-000i-000i-000i-000i-235L

Cheers,
Fabrizio
________________________________
From: users <users-bounces at lists.quantum-espresso.org> on behalf of Jibiao Li <jibiaoli at foxmail.com>
Sent: Monday, December 12, 2022 10:03 AM
To: users <users at lists.quantum-espresso.org>
Subject: Re: [QE-users] Run error of M06 exchange with libxc 4.3.4

Hi, Fabrizio

I found the following information in the link you provided,

MGGA_C_M06 (id=235): Minnesota M06 correlation functional

However, the calculation does work when I use input_dft="MGGA_C_M06" or input_dft="id=235"

In the user guide, I also found the following description, but where I can find the index notation like "XC-000I-000I-101L-130L-000I-000I" for M06 functional?

"In order to use libxc functionals, you can enforce them from input by including the input_dft string in the system namelist. Starting from v7.0 of QUANTUM ESPRESSO the only allowed notation for DFTs that include Libxc terms is the index one. For example, to use the libxc version of the PBE functional (both exchange and correlation):

input_dft = `XC-000I-000I-101L-130L-000I-000I'

The letters I or L next to each ID stand for Internal and libxc. This is equivalent to the old full-name notation:

Best
________________________________

Jibiao Li

Department of Materials Science and Engineering

Yangtze Normal University

Juxian Avenue 16, Fuling, Chongqing, China 408100

Scopus Research ID: 54944118000<https://www.scopus.com/authid/detail.uri?authorId=54944118000>

Web of Science Research ID: F-1905-2016<https://publons.com/researcher/2283103/jibiao-li/>

<https://publons.com/researcher/2283103/jibiao-li/>

------------------ Original ------------------
From: "Quantum ESPRESSO users Forum" <faferrar at sissa.it>;
Date: Mon, Dec 12, 2022 04:55 PM
To: "Quantum ESPRESSO users Forum"<users at lists.quantum-espresso.org>;
Subject: Re: [QE-users] Run error of M06 exchange with libxc 4.3.4

Dear Jibiao,
I stress the following lines from the user guide:

The complete list of libxc functionals (and their IDs) is available at:

https://www.tddft.org/programs/libxc/functionals/

So you can find there the IDs to put in the index notation.

Cheers,
Fabrizio
________________________________
From: users <users-bounces at lists.quantum-espresso.org> on behalf of Jibiao Li <jibiaoli at foxmail.com>
Sent: Friday, December 9, 2022 12:25 AM
To: users <users at lists.quantum-espresso.org>
Subject: Re: [QE-users] Run error of M06 exchange with libxc 4.3.4

Dear All,

In the user guide, I found the following information, but where can I get the index notation for M06 exchange included in libxc?

"In order to use libxc functionals, you can enforce them from input by including the input_dft string in the system namelist. Starting from v7.0 of QUANTUM ESPRESSO the only allowed notation for DFTs that include Libxc terms is the index one. For example, to use the libxc version of the PBE functional (both exchange and correlation):

input_dft = `XC-000I-000I-101L-130L-000I-000I'

The letters I or L next to each ID stand for Internal and libxc. This is equivalent to the old full-name notation:

input_dft = `gga_x_pbe gga_c_pbe'   ***OLD***

The order must be the usual one, namely LDA exchange, LDA correlation, GGA exchange, GGA correlation, MGGA exchange, MGGA correlation. libxc exchange+correlation functionals can be put in the exchange or in the correlation slot with no difference.
The reason why the full-name notation has been disabled is to eliminate the risk of overlaps among different names (occurring especially when combinations of internal and libxc DFTs are used).
The complete list of libxc functionals (and their IDs) is available at:

https://www.tddft.org/programs/libxc/functionals/

Combinations of QUANTUM ESPRESSO and libxc functionals are allowed in PW, but some attention has to be paid to their reciprocal compatibility (see section below).
For example, the internal exchange term of PBE together with the correlation term of PBE in libxc is obtained by:

input_dft = `XC-001I-000I-003L-130L-000I-000I'

which corresponds to the old:

input_dft = `sla pbx gga_c_pbe'   ***OLD***

Note that when using GGA internal functionals you must always specify the LDA term too, while it is not the case for the libxc ones.
Abbreviations are allowed when zero tails are present. The above example is still valid by putting:

input_dft = `XC-001I-000I-003L-130L'

since no MGGA terms are present.
Non-local terms can be included by just adding their name after the index notation, for example:

input_dft=`XC-001i-004i-013i-vdw2'"

Best

________________________________

Jibiao Li

Department of Materials Science and Engineering

Yangtze Normal University

Juxian Avenue 16, Fuling, Chongqing, China 408100

Scopus Research ID: 54944118000<https://www.scopus.com/authid/detail.uri?authorId=54944118000>

Web of Science Research ID: F-1905-2016<https://publons.com/researcher/2283103/jibiao-li/>

<https://publons.com/researcher/2283103/jibiao-li/>

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