[QE-users] Effect of nbnd on vc-relax

[Jing Lian Ng]

Hello all,

I am trying to do a vc-relax calculation on y-Fe2O3 with 160 atoms.
Currently I am facing convergence issue with the input script below. With
nbnd = 800, the calculation usually finishes in ~ 1 hr on a supercomputer,
but fails to reach convergence even on the first BFGS step. When I removed
the nbnd parameter, QE automatically set the number of Kohn-Sham states to
960 and the calculation was able to proceed. However, the relaxation
calculation is taking more than 72 hours and hasn't reached completion (It
is still running now, on 15th BFGS cycle). Is this a normal timescale for a
system with >100 atoms? And how should I determine an appropriate value of
nbnd before starting any calculation?

 Input Script 
&SYSTEM
   ibrav   = 14
   A   = 8.48998
   B   = 8.48998
   C   = 25.46994
   cosAB   = 0
   cosAC   = 0
   cosBC   = 0
   nat = 160
   ntyp= 3
   ecutwfc = 65
   ecutrho = 780
   nbnd= 800
   occupations = 'smearing'
   degauss = 0.001
   smearing= 'mv'
   nspin   = 2
   starting_magnetization(1) = 0.5
   starting_magnetization(2) = -0.5
   starting_magnetization(3) = 0
 /
 &ELECTRONS
   conv_thr= 0.1
   mixing_mode = 'plain'
   mixing_beta = 0.3
   electron_maxstep = 200
 /
 &IONS
 /
 &CELL
   !cell_dofree = 'volume'
 /
ATOMIC_SPECIES
  FeO   55.84500  Fe.pbesol-spn-kjpaw_psl.0.2.1.UPF
  FeT   55.84500  Fe.pbesol-spn-kjpaw_psl.0.2.1.UPF
O   15.99900  O.pbesol-n-kjpaw_psl.0.1.UPF
##

Thanks,
Jing Lian Ng
Graduate student at CHE, University of Texas at Austin
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Re: [QE-users] Problem with convergence

[imane BEZZAOUI]

Dear Iiuri

Thank you for your replying,

I used  q6.6 version there are my input file and my output file.

For my output, I haven't finished executing,  it because it obviously
didn't converge

 ex.in


 ascf.out


*---*
*Imane BEZZAOUI PhD Student*
*---*
*Laboratory of Industrial Engineering and Seismic Engineering.*
*National School of Applied Science. *
*University Mohammed First Oujda, Morocco.*
*---*
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Re: [QE-users] [SPAM] Calculation of static dielectric tensor

[Lorenzo Paulatto]

The static dielectric matrix is computed by the phonon (ph.x) code, with option 
epsil=.true., you can set trans=.false. if you want to avoid computing also the 
phonons.

The epsil.x code computes the dynamical dielectric matrix (with a sum over 
empty states if I remember correctly). It should match the other in the low 
energy limit.

Hth

On June 2, 2023 10:01:45 p.m. GMT+02:00, "Филанович Антон" 
 wrote:
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[QE-users] [SPAM] static dielectric tensor

[Anton Filanovich]

Dear community, I need to calculate electronic and ionic contribution to the static dielectric tensor - similar to what is done in VASP as described here  vasp.at/wiki/index.php/LEPSILON  . Do I understand correctly that in epsr.dat file, which we obtain after a calculation with epsilon.x, three values at zero frequency correspond to the diagonal elements of the static dielectric tensor? However, even if is true, how can I obtain electronic/ionic contributions?   Thanks in advance,Anton P.S. Sorry for my first two e-mails, which were detected as SPAM, this occured because I put a complete URL to the VASP website.
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[QE-users] [SPAM] static dielectric tensor

[Anton Filanovich]

 Dear community,I need to calculate electronic and ionic contribution to the static dielectric tensor - similar to what is done in VASP as described here https://www.vasp.at/wiki/index.php/LEPSILON . Do I understand correctly that in epsr.dat file, which we obtain after a calculation with epsilon.x, three values at zero frequency correspond to the diagonal elements of the static dielectric tensor? However, even if is true, how can I obtain electronic/ionic contributions? Thanks in advance,Anton
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