[QE-users] Alpha_mix not resolving ph.x convergence failure

Jessica Johnson jj611 at soe.rutgers.edu
Mon Jul 11 21:41:46 CEST 2022


Hello,

I wanted to follow up on this thread with a solution to my previous issue and a related, but new issue.

For the system I posted about previously, (the 1T phase of MoS2 with H adsorption), I was able to get the phonons calculation to converge by reducing conv_thr in the scf calculation even further. It was 1e-10; lowering it to 1e-16 led my subsequent phonons calculation to complete.

I am also looking at the 1H phase of MoS2. I am racking my brain, but I cannot figure out what I am doing wrong. I've tried: 1) adjusting alpha_mix(i), 2) lowering the convergence threshold in the scf step, 3) gaussian smearing or no gaussian smearing, 4) increasing the threshold in the ph.x step, 5) repeating the relaxation step with a tighter conv_thr, 6) increasing "maxter" in .f90 file, and possibly some other parameters I am forgetting at the moment.

I am using the norm-conserving, scalar relativistic PBE potential from pseudo dojo (was my choice in pp or functional the mistake?). Please find my input files below:

 &CONTROL
   calculation     =  'scf'
   prefix          =  '1H_0'
   pseudo_dir      =  '.'
   title           =  '1H layers'
   verbosity       =  'high'
 /

 &SYSTEM
   A               =  6.385866
   B               =  6.385866
   C               =  14
   cosAB           =  -0.5
   cosAC           =  0
   cosBC           =  0
   !degauss         =  0.005
   ecutrho         =  368
   ecutwfc         =  92
   ibrav           =  4
   input_dft       =  'BEEF-vdW'
   nat             =  12
   ntyp            =  2
   !occupations     =  'smearing'
   !smearing        =  'gaussian'
 /

 &ELECTRONS
   conv_thr        =  5e-15
 /

 &IONS
 /

 &CELL
   cell_dofree     =  'epitaxial_ab'
 /

ATOMIC_SPECIES
  Mo    95.95   Mo_HER.upf
  S    32.066   S_HER.upf


ATOMIC_POSITIONS (crystal)
Mo           -0.0000000000       -0.0000000000        0.2500001541
S             0.1666664325        0.3333333650        0.3617461091
S             0.1666664465        0.3333333930        0.1382538265
Mo            0.0000001753        0.5000000876        0.2499999935
S             0.1666664325        0.8333335675        0.3617461091
S             0.1666664465        0.8333335535        0.1382538265
Mo            0.4999999124       -0.0000001753        0.2499999935
S             0.6666665000        0.3333335000        0.3617463074
S             0.6666665000        0.3333335000        0.1382537513
Mo            0.4999999124        0.5000000876        0.2499999935
S             0.6666666350        0.8333335675        0.3617461091
S             0.6666666070        0.8333335535        0.1382538265

K_POINTS (automatic)
  8   8   1   0   0   0

=============================================================

Phonon calculation 1H_0

&inputph
  prefix        = '1H_0'
  fildyn        = '1H_0.1.G'
  tr2_ph        = 1.0d-12
  alpha_mix(1)  = .4
  alpha_mix(10) = .2
  alpha_mix(15) = .1
/
0.0 0.0 0.0

Thank you again for your insights.

Jessica Johnson
graduate student
Materials Science and Engineering Department
Rutgers University, New Brunswick, New Jersey
________________________________
From: Jessica Johnson <jj611 at soe.rutgers.edu>
Sent: Monday, May 16, 2022 3:46 PM
To: users at lists.quantum-espresso.org <users at lists.quantum-espresso.org>
Subject: Re: [QE-users] Alpha_mix not resolving ph.x convergence failure

I see- that may do the trick. My university platform will be down for a couple of days for scheduled maintenance, but I will implement this suggestion as soon as it is back up.

Thank you very much for your help,
Jessica
________________________________
From: users <users-bounces at lists.quantum-espresso.org> on behalf of Pietro Davide Delugas <pdelugas at sissa.it>
Sent: Friday, May 13, 2022 2:46 AM
To: users at lists.quantum-espresso.org <users at lists.quantum-espresso.org>
Subject: Re: [QE-users] Alpha_mix not resolving ph.x convergence failure

Hello
many times it works better if you   reduce alpha_mix gradually. For example with

alpha_mix(10) = 0.3

and

alpha_mix (15) = 0.1

you use default value for alpha_mix in first 10 iterations, then  you reduce it to 0.3, and to 0.1 after 15th iteration.

Pietro

On 5/13/22 00:06, Jessica Johnson wrote:
Hello QE users,

I am having trouble converging a phonons calculation. The archives indicate that many users were able to solve this problem reducing the default value of alpha_mix(1) to .1 or .2. I have tried many values from .01 - .9 and I end up with the calculation being unable to converge. In addition, I have lowered the convergence threshold for the scf calculation thinking that would set up the phonons calculation to converge more easily. I have also varied the nq1, nq2, k1 and k2 values. Neither of the latter two changes made much difference

I am using espresso + d3q (version number I am unsure of, however the release date is Dec. 12, 2021).

My ultimate goal is to use the d3_q2r.x and d3_qha.x executables to compute adsorption of H onto MoS2 layers.

Here are my pw.x and ph.x input files for H adsorbed onto the Mo site:
________________________________________________________

&CONTROL
   calculation     =  'scf'
   prefix          =  '1T_H_Mo_0'
   pseudo_dir      =  '.'
   title           =  '1T layers'
   verbosity       =  'high'
 /

 &SYSTEM
   A               =  6.385866
   B               =  6.385866
   C               =  14
   cosAB           =  -0.5
   cosAC           =  0
   cosBC           =  0
   degauss         =  0.005
   ecutrho         =  368
   ecutwfc         =  92
   ibrav           =  4
   input_dft       =  'BEEF-vdW'
   nat             =  13
   ntyp            =  3
   occupations     =  'smearing'
   smearing        =  'gaussian'
 /

 &ELECTRONS
   conv_thr        =  1e-10
 /

 &IONS
 /

 &CELL
   cell_dofree     =  'epitaxial_ab'
 /

ATOMIC_SPECIES
  Mo    95.95   Mo_HER.upf
  S    32.066   S_HER.upf
  H    1.00794   H_HER.upf


ATOMIC_POSITIONS crystal
Mo            0.0000010000       -0.0000010000        0.2432527978
S             0.3387936710        0.1693960855        0.1415931532
S             0.1716523937        0.3433032874        0.3652990281
H            -0.0000005000        0.0000000000        0.3685376338
Mo            0.4770138961       -0.0459752078        0.2481206178
S             0.8306049145        0.1693960855        0.1415931532
S             0.6666670000        0.3333325000        0.3420643699
Mo            0.4770138961        0.5229861039        0.2481206178
S             0.8306049145        0.6612073290        0.1415931532
S             0.6566962126        0.8283471063        0.3652990281
Mo            0.0459752078        0.5229861039        0.2481206178
S             0.3333345000        0.6666665000        0.1232508011
S             0.1716523937        0.8283471063        0.3652990281

K_POINTS automatic
  4   4   1   0   0   0

_____________________________________________________________


Phonon calculation 1T_H_Mo_0

&inputph
  prefix        = '1T_H_Mo_0'
  fildyn        = '1T_H_Mo_0.1.G'
  tr2_ph        = 1.0d-14
  alpha_mix(1)  = .1
  ldisp         = .true.
  nq1           = 4
  nq2           = 4
  nq3           = 1
/

___________________________________________________________

Thank you in advance for your help on this matter, as it is one of the tougher ones I have encountered using QE.

Jessica Johnson
graduate student
Materials Science and Engineering Department
Rutgers University, New Brunswick, New Jersey



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