[QE-users] Convergence and restart of hp.x

[Timrov Iurii]

Dear Prasenjit,


For the HP calculation you can try alpha_mix(1)=0.1 or even 0.05. Also try to use niter_max = 200 or 300.


For the SCF calculation degauss=0.004 Ry is very small. The system is gapped or metallic at the PBE level? Maybe you can try larger values for degauss? Also you can try higher values for ecutwfc and ecutrho.


> When I go to higher k-mesh, some of the k-points are not converging (within 100 iterations).


Do you mean some q points that do not converge?


Greetings,

Iurii


--
Dr. Iurii Timrov
Postdoctoral Researcher
STI - IMX - THEOS and NCCR - MARVEL
Swiss Federal Institute of Technology Lausanne (EPFL)
CH-1015 Lausanne, Switzerland
+41 21 69 34 881
http://people.epfl.ch/265334
________________________________
From: users <users-bounces at lists.quantum-espresso.org> on behalf of Prasenjit Ghosh <prasenjit.jnc at gmail.com>
Sent: Monday, August 17, 2020 10:57:41 AM
To: Quantum ESPRESSO users Forum
Subject: Re: [QE-users] Convergence and restart of hp.x

Dear Iurii,

Thanks for your prompt response. I would just like to point out that the calculation is converging for a smaller q-mesh, 2x2x2 in my case. When I go to higher k-mesh, some of the k-points are not converging (within 100 iterations). I have not yet tried increasing the no. of iterations.

Given below is the input scf file:

&control
    calculation = 'scf'
    restart_mode='from_scratch',
    prefix='tifesb',
    pseudo_dir = './',
    outdir= './tmp_tifesb'

 /
 &system
    ibrav= 1, celldm(1)= 11.343477089,
     nat=12, ntyp= 3,
    ecutwfc = 60, ecutrho=500,
   occupations='smearing'
   smearing='mv'
   degauss=0.004
   lda_plus_u=.true.
   lda_plus_u_kind=0
   U_projection_type='atomic'
   Hubbard_U(2)=1.0d-10
   Hubbard_U(3)=1.0d-10
 /
 &electrons
    diagonalization='david'
    mixing_mode = 'local-TF'
    mixing_beta = 0.3
    conv_thr =  1.0d-07
 /
&ions
/
&cell
cell_dofree='xyz'
/
ATOMIC_SPECIES
Sb 50.9415    Sb.pbe-n-rrkjus_psl.1.0.0.UPF
Fe 26.981539  Fe.pbe-sp-van_mit.UPF
Ti 26.981539  Ti.pbe-spn-rrkjus_psl.1.0.0.UPF

ATOMIC_POSITIONS (crystal)
Ti   0.000000000    0.000000000    0.000000000
Ti   0.500000000    0.500000000    0.000000000
Ti   0.000000000    0.500000000    0.500000000
Ti   0.500000000    0.000000000    0.500000000
Fe   0.250000000    0.250000000    0.250000000
Fe   0.750000000    0.750000000    0.250000000
Fe   0.250000000    0.750000000    0.750000000
Fe   0.750000000    0.250000000    0.750000000
Sb   0.500000000    0.500000000    0.500000000
Sb   1.000000000    1.000000000    0.500000000
Sb   0.500000000    1.000000000    1.000000000
Sb   1.000000000    0.500000000    1.000000000
K_POINTS {automatic}
12 12 12 1 1 1

The input for the hp.x is given below:

&inputhp
prefix='tifesb'
outdir='./tmp_tifesb'
nq1=3, nq2=3, nq3=3
conv_thr_chi = 1.0d-5
iverbosity = 2
alpha_mix(1)=0.2
/

With regards,
Prasenjit

On Mon, 17 Aug 2020 at 13:58, Timrov Iurii <iurii.timrov at epfl.ch<mailto:iurii.timrov at epfl.ch>> wrote:

Dear Prasenjit Ghosh,


> Can someone please indicate other input parameters that can be tuned to reach convergence?

You can check the HP documentation, but there are not that many parameters that can help to converge the HP calculation. Typically, the reason why HP does not converge is because there are problems with the SCF calculation. Can you share with us your input files for PWscf and HP? This will help us to understand what can be the problem.

> Also is there a way to restart the hp.x calculations?


Yes. Check examples 7 in the HP repository. You can restart from a q point which was not converged (note that for this q point the calculation will be done from scratch).


Greetings,

Iurii


--
Dr. Iurii Timrov
Postdoctoral Researcher
STI - IMX - THEOS and NCCR - MARVEL
Swiss Federal Institute of Technology Lausanne (EPFL)
CH-1015 Lausanne, Switzerland
+41 21 69 34 881
http://people.epfl.ch/265334
________________________________
From: users <users-bounces at lists.quantum-espresso.org<mailto:users-bounces at lists.quantum-espresso.org>> on behalf of Prasenjit Ghosh <prasenjit.jnc at gmail.com<mailto:prasenjit.jnc at gmail.com>>
Sent: Monday, August 17, 2020 5:10:56 AM
To: Quantum Espresso users Forum
Subject: [QE-users] Convergence and restart of hp.x

Dear all,

I am using hp.x to compute the U value. I have two types of Hubbard atoms in my unit cell. I am using qe-6.5.
For my system with a 2x2x2 q-grid, the calculations converge. However, the moment I use a denser grid, the calculations don't converge, even after playing around with the mixing parameter.

Can someone please indicate other input parameters that can be tuned to reach convergence?
Also is there a way to restart the hp.x calculations?

With regards,
Prasenjit

--
PRASENJIT GHOSH,
IISER Pune,
Dr. Homi Bhabha Road, Pashan
Pune, Maharashtra 411008, India

Phone: +91 (20) 2590 8203
Fax: +91 (20) 2589 9790
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--
PRASENJIT GHOSH,
IISER Pune,
Dr. Homi Bhabha Road, Pashan
Pune, Maharashtra 411008, India

Phone: +91 (20) 2590 8203
Fax: +91 (20) 2589 9790
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