[QE-users] vc-relax with PBE0 not converging

Wed Feb 10 15:58:20 CET 2021

Hello,

I finally turned to CP2K to use PBE0-D3. The equivalent of vc-relax worked for my molecular crystal and the structure converged. I did an all-electron simulation and have not yet used pseudopotentials.

So I really wonder what's wrong with QE, concerning the same simulation using hybrid functionals?

Best,
Xavier
________________________________
From: Bidault, Xavier <xavbdlt at uic.edu>
Sent: Tuesday, February 2, 2021 2:05 PM
To: Quantum ESPRESSO users Forum <users at lists.quantum-espresso.org>
Subject: Re: [QE-users] vc-relax with PBE0 not converging

Hello,

@Giovani: I have tested SCAN-rvv10 with the PP provided in the link. vc-relax works very well with it. Thank you! I just had to use a cutoff at least 200 Ry to get less than 2 meV/atom error.

@All: I'm currently trying B3LYP-D3 (with mt PP files provided on QE website and cutoff larger than 140 Ry), and I get the same oscillations with no damping during a vc-relax. So it's not only PBE0. Something must be wrong with hybrid functionals and vc-relax. Does someone else get the same issue with hybrid functionals? Or am I missing a parameter setting? Below is the main part of the input script (without atom positions). Does someone see something obvious missing to make PBE0 run correctly with vc-relax for a molecular crystal (monoclinic insulator)? Maybe the bfgs algorithm to change?

&control
    calculation='vc-relax',
    restart_mode='from_scratch',
    prefix='vc-relax_90_f4e5'
    pseudo_dir = './../../pseudo/',
    forc_conv_thr = 1.0d-4,
    etot_conv_thr = 1.0d-5,
    nstep = 1000
 /
 &system
    ibrav=-12,
    celldm(1)=  12.331406938,
    celldm(2)=   1.691349322,
    celldm(3)=   1.128495901,
    celldm(5)=  -0.2193360205,
    nat=  56,
    ntyp= 4,
    input_dft = 'PBE0',
    vdw_corr = 'dft-d3',
    ecutwfc  = 90              ! 2 meV/atom error
    ecutfock = 90
    nqx1 = 1
    nqx2 = 1
    nqx3 = 1
 /
 &electrons
    conv_thr =1.0d-8
/
 &ions
    ion_dynamics = 'bfgs'
/
 &cell
    cell_dynamics = 'bfgs',
    cell_dofree = 'ibrav',
    press = 0.0,
    press_conv_thr = 0.1
/
K_POINTS AUTOMATIC
3 2 3 1 1 1
ATOMIC_SPECIES
 C 12.011 C_ONCV_PBE-1.2.upf
 H  1.008 H_ONCV_PBE-1.2.upf
 O 15.999 O_ONCV_PBE-1.2.upf
 N 14.007 N_ONCV_PBE-1.2.upf
________________________________
From: users <users-bounces at lists.quantum-espresso.org> on behalf of Giovani Rech <gio.pi.rech at gmail.com>
Sent: Saturday, January 30, 2021 12:28 PM
To: Quantum ESPRESSO users Forum <users at lists.quantum-espresso.org>
Subject: Re: [QE-users] vc-relax with PBE0 not converging

Dear Xavier,
I've faced the same issue a while back while using scan-rvv10. The pressure would not converge with the pseudo-potential that I was using (ONCV). For my case (https://www.mail-archive.com/users@lists.quantum-espresso.org/msg36102.html<https://nam04.safelinks.protection.outlook.com/?url=https%3A%2F%2Fwww.mail-archive.com%2Fusers%40lists.quantum-espresso.org%2Fmsg36102.html&data=04%7C01%7Cxavbdlt%40uic.edu%7C709e6f580f424bb29eaa08d8c54d02ce%7Ce202cd477a564baa99e3e3b71a7c77dd%7C0%7C0%7C637476282598609312%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C2000&sdata=OsEnbXq4P4iScMir%2FNRrGlXWhHbpSGE%2BaporX1oPr7c%3D&reserved=0>) the issue was solved when I changed the PP to one that was built using SCAN.
Please try to use one of the PP found here: https://yaoyi92.github.io/scan-tm-pseudopotentials.html<https://nam04.safelinks.protection.outlook.com/?url=https%3A%2F%2Fyaoyi92.github.io%2Fscan-tm-pseudopotentials.html&data=04%7C01%7Cxavbdlt%40uic.edu%7C709e6f580f424bb29eaa08d8c54d02ce%7Ce202cd477a564baa99e3e3b71a7c77dd%7C0%7C0%7C637476282598619268%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C2000&sdata=XGWTblBQMpn92c3Cq9EuiNReSQAkxI3r5eZI97%2FN0sU%3D&reserved=0> or even look for a PP built using PBE0.

Hope this helps,

Giovani Rech

Materials Physics and Advanced Ceramics
Universidade de Caxias do Sul
95070-560 Caxias do Sul - RS, Brazil
orcid.org/0000-0003-0476-2056<https://nam04.safelinks.protection.outlook.com/?url=http%3A%2F%2Forcid.org%2F0000-0003-0476-2056&data=04%7C01%7Cxavbdlt%40uic.edu%7C709e6f580f424bb29eaa08d8c54d02ce%7Ce202cd477a564baa99e3e3b71a7c77dd%7C0%7C0%7C637476282598619268%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C2000&sdata=617XlpxPnbTJLbgJhYF7NAE7zb%2FSMyJIEQF9Fbw6IU0%3D&reserved=0>

On Mon, Jan 25, 2021 at 12:19 PM Bidault, Xavier <xavbdlt at uic.edu<mailto:xavbdlt at uic.edu>> wrote:
Hello,

I have a molecular crystal (1 unit cell = 56 atoms). I use SG15 ONCV 1.2 pseudopotential and Grimme D2 correction.
Using vc-relax with PBE, the structure converges, no problem.
But with PBE0, density and pressure oscillate without dampening (see figure below - Pressure remains negative, and not close to zero). Is there any particular strategy with PBE0?

  *   vc-relax with PBE and then starting from the result and use PBE0?
  *   relax with PBE0 and then vc-relax?
  *   any simulation parameter to change (ion dynamics and/or cell dynamics - currently BFGS)?
  *   any strategy with PBE0?

[cid:1775486a5dacb971f161]
Thank you,
Xavier

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