[QE-users] using Hybrid functional in QE
Giuseppe Mattioli
giuseppe.mattioli at ism.cnr.it
Mon Jan 9 00:08:59 CET 2023
It is true, in principle you can use whatever PP and overrule the xc
functional using "input_dft". However, it is intuitively wise (and can
be confirmed doing a few simple tests in simple systems against
well-converged all-electron calculations) to use PPs generated using
an xc functional as close as possible to the hybrid functional. For
example, in the case of PBE0 you have 75% of PBE exchange and 100% of
PBE correlations, so that it is reasonable to use PBE PPs. The same
holds for B3LYP and BLYP.
HTH
Giuseppe
Quoting Abdeslam Houari via users <users at lists.quantum-espresso.org>:
> When you use "input_dft", this automatically overwrite the
> xc-functional of the PP (this is well explained in the PWscf
> manuel). As far as I understood (we discussed this few weeks ago in
> the forum), whatever the PP you are using, the "input_dft" will run
> hybrid calculation according to it's functional definition and
> discard the PP (For example PBE0: 1/4 EXX and (3/4 E_X + E_C) at the
> PBE level). If that's true, this means that you can use any PP.
> I hope this is helpful
>
>
>
> =========================================
> Dr. Abdesalem
> HOUARI-------------------------------------------------------------------------------------------
> Department of physics, Theoretical Physics Laboratory
> University of Bejaia-06000. Algeria.
> E-mail: abdeslam.houari at univ-bejaia.dz & habdslam at yahoo.fr
> https://sites.google.com/site/houariabdeslam/homepage
> =========================================
>
>
> On Saturday, 7 January 2023 at 01:33:40 am GMT+1, Rameswar
> Bhattacharjee <rb1820 at georgetown.edu> wrote:
>
> Hi Giuseppe,Thank you very much for sharing the input sample and
> your valuable suggestion. I will try to run a calculation with
> B3LYP/PBE0 and will see how it goes.
> Rameswar
> On Fri, Jan 6, 2023 at 1:58 PM Giuseppe Mattioli
> <giuseppe.mattioli at ism.cnr.it> wrote:
>
>
> Dear Simon
> The lack of pseudopotentials generated using a hybrid functional does
> not represent a significant source of error when using such
> functionals in calculations. I've run tons of B3LYP calculations using
> BLYP pseudopotentals and of PBE0 or HSE calculations using PBE
> pseudopotentials. PBE PPs are easier to find, while BLYP ones may be
> more difficult and sometimes you must (re)generate them yourself.
>
> The input should be something like this (but check all the options in
> the pw input guide as they may be suitable/not suitable for your
> calculations):
>
> &control
> calculation = 'relax'
> restart_mode='from_scratch',
> prefix='$FILE',
> pseudo_dir = '$PSEUDO_DIR/',
> outdir='$TMP_DIR/',
> nstep=200,
> /
> &system
> ibrav=1, celldm(1)=40.0000,
> nat=87 ntyp=4,
> ecutwfc=90.0,
> ecutfock=130.0,
> occupations='smearing', degauss=0.01,
> nspin=1,
> input_dft='b3lyp'
> vdw_corr='grimme-d3',
> /
> &electrons
> diagonalization='david',
> mixing_mode='plain',
> mixing_beta=0.1,
> conv_thr=1.0d-6,
> electron_maxstep=100
> adaptive_thr=.true.
> /
> &ions
> ion_dynamics='bfgs'
> /
> ATOMIC_SPECIES
> O 15.999 O.blyp-mt.UPF
> N 14.007 N.blyp-mt.UPF
> C 12.011 C.blyp-mt.UPF
> H 1.008 H.blyp-vbc.UPF
> ATOMIC_POSITIONS {angstrom}
> ...
> K_POINTS {gamma}
>
> NB: I always recommend the use of norm-conserving pseudopotentials (in
> this case they are rather old but very well tested pseudopotentials
> that used to be in the QE repo, but you can generate BLYP PPs using
> the "atomic" ld1.x code and the PSlibrary, or even the ONCV generation
> code) when performing EXX calculations.
> HTH
> Giuseppe
>
> Quoting Rameswar Bhattacharjee <rb1820 at georgetown.edu>:
>
>> Hi Simon,
>> Thank you for the information. I have gone through the input_dft and it
>> looks like I can use PBE0 or B3LYP. But I am not sure for that case which
>> pseudopotential I should use. Could you (or anyone) have a sample input to
>> run a QUE calculation using the B3LYP functional? That would be very
>> helpful. Thank you
>>
>> Rameswar
>>
>> On Fri, Jan 6, 2023 at 11:34 AM Simon Imanuel Rombauer <
>> simon.rombauer at student.uni-augsburg.de> wrote:
>>
>>> Hello Rameswar,
>>>
>>> see 'input_dft' option in the documentation, see Modules/funct.f90 for
>>> possible functionals.
>>> Best,
>>> Simon
>>>
>>> Am Freitag, Januar 06, 2023 17:00 CET, schrieb Rameswar Bhattacharjee <
>>> rb1820 at georgetown.edu>:
>>>
>>> > Hi Everyone,
>>> > I wonder if I can use hybrid functionals such as PBE0 or B3LYP in QE for
>>> > ground state calculation. All the pseudopotentials I found on the website
>>> > are for PBE. But I need an exchange-correlation functional (not pure) to
>>> > calculate the band gap more accurately.
>>> >
>>> > Any suggestions would be appreciated. Thank you.
>>> >
>>> > Rameswar Bhattacharjee
>>> > PostDoc
>>> > Georgetown University
>>>
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>
>
>
> GIUSEPPE MATTIOLI
> CNR - ISTITUTO DI STRUTTURA DELLA MATERIA
> Via Salaria Km 29,300 - C.P. 10
> I-00015 - Monterotondo Scalo (RM)
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> E-mail: <giuseppe.mattioli at ism.cnr.it>
>
> _______________________________________________
> The Quantum ESPRESSO community stands by the Ukrainian
> people and expresses its concerns about the devastating
> effects that the Russian military offensive has on their
> country and on the free and peaceful scientific, cultural,
> and economic cooperation amongst peoples
> _______________________________________________
> Quantum ESPRESSO is supported by MaX (www.max-centre.eu)
> users mailing list users at lists.quantum-espresso.org
> https://lists.quantum-espresso.org/mailman/listinfo/users
>
> _______________________________________________
> The Quantum ESPRESSO community stands by the Ukrainian
> people and expresses its concerns about the devastating
> effects that the Russian military offensive has on their
> country and on the free and peaceful scientific, cultural,
> and economic cooperation amongst peoples
> _______________________________________________
> Quantum ESPRESSO is supported by MaX (www.max-centre.eu)
> users mailing list users at lists.quantum-espresso.org
> https://lists.quantum-espresso.org/mailman/listinfo/users
GIUSEPPE MATTIOLI
CNR - ISTITUTO DI STRUTTURA DELLA MATERIA
Via Salaria Km 29,300 - C.P. 10
I-00015 - Monterotondo Scalo (RM)
Mob (*preferred*) +39 373 7305625
Tel + 39 06 90672342 - Fax +39 06 90672316
E-mail: <giuseppe.mattioli at ism.cnr.it>
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