[QE-users] ESM does not converge

[Weitzner, Stephen Eric]

Dear Antonio,

Can you send the output as well to show how the SCF convergence goes?

A few simple things you could try:


  1.  Turn off symmetry with nosym = .TRUE. I believe this is a requirement for using ESM.
  2.  Test with a gamma centered k-grid. I cannot remember exactly, but it may be necessary to include the gamma point in BZ sampling for ESM to work properly. Someone may correct me here if I am wrong.
  3.  Reduce the total charge you are testing. A total charge of 1 excess electron is a pretty large surface charge density for your surface primitive cell. Maybe try with tot_charge = -0.1 or smaller magnitude to see if this converges.
  4.  You could also try changing your smearing to ‘mv’ to use Marzari-Vanderbilt smearing and use a slightly larger broadening, e.g., degauss = 0.01 or degauss = 0.008 to see if this improves scf convergence.


Hope that helps.

--
Stephen Weitzner, PhD
Postdoctoral Research Scientist
Quantum Simulations Group
Lawrence Livermore National Laboratory

T : (925) 422-4449
E : weitzner1 at llnl.gov


From: users <users-bounces at lists.quantum-espresso.org> on behalf of Antonio Crepaldi <antonio.crepaldi.lanza at gmail.com>
Reply-To: Quantum ESPRESSO users Forum <users at lists.quantum-espresso.org>
Date: Wednesday, May 13, 2020 at 2:32 PM
To: "users at lists.quantum-espresso.org" <users at lists.quantum-espresso.org>
Subject: [QE-users] ESM does not converge

Dear All,

I'm computing a Cu slab with esm_bc='bc3' with total charge = -1. However, whenever the charge is !=0 i cannot converge the scf. Here you can find my input file

&CONTROL
   calculation      = 'scf'
   wf_collect       = .true.
   nstep            = 1000
   outdir           = './Cu_esm3/'
   prefix           = 'Cu_esm3'
   etot_conv_thr    = 0.0001
   forc_conv_thr    = 0.001
   pseudo_dir       = '/homel/acrepaldi/pseudo'
/
&SYSTEM
   ibrav            = 4
   ecutwfc          = 34
   ecutrho          = 340
   occupations      = 'smearing'
   degauss          = 0.002
   smearing         = 'gaussian'
   ntyp             = 1
   nat              = 7
   celldm(3)        = 11.710490425008139
   celldm(1)        = 4.841111
   assume_isolated='esm',
   esm_bc='bc3'
   tot_charge = -1
/
&ELECTRONS
   electron_maxstep = 200
   conv_thr         = 1e-08
   mixing_mode      = 'local-TF'
   mixing_beta      = 0.2
/
ATOMIC_SPECIES
Cu 63.546 Cu_pbe_v1.2.uspp.F.UPF

ATOMIC_POSITIONS angstrom
Cu 0.0000000000 0.0000000000 -6.2637166039
Cu 1.2809033158 0.7395306152 -4.1821166321
Cu 0.0000000013 1.4790602298 -2.0948941353
Cu 0.0000000000 0.0000000000 0.0009999887
Cu 1.2809033158 0.7395306152 2.0968941353
Cu 0.0000000013 1.4790602298 4.1841166096
Cu 0.0000000000 0.0000000000 6.2657166039

K_POINTS automatic
11 11 1  1 1 0

I do not understand where I am going wrong.
Thank you very much for your help.
Sincerely

Antonio Crepaldi-Lanza

--
Departmente of Physics "Aldo Moro"
University of Bari
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