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Failing to relax a 2D structure

Posted: Mon Jan 27, 2020 2:30 pm
Dear experts and users,

I've been trying to relax a 2D Ga structure with no success. Could you please indicate what might be wrong?
The structure has been successfully calculated by me or my colleagues in other DFT packages (QE, VASP).
Thus, I started off with an almost relaxed structure, and I expected it to be fully relaxed in ABINIT within just a few steps.
Indeed, the first step indicated forces of 10^(-5) Ha/bohr, but after a couple of quickly converging relaxation steps the situation got quite bad: all the following steps are not converging well (oscillating residm/vres) and forces are going bad (I terminate the job when forces deteriorate to 10^(-1) Ha/bohr ).
I tried ionmov = 2,3, different versions of Abinit, increasing nband, ecut, ngkpt. Nothing seems to work.

Below I provide an example of my input file:

Code: Select all

optcell  9
ionmov   2
tolmxf   5.0d-5
strfact  10
ntime    500
dilatmx  1.1
ecutsm   0.5
npulayit 25
nline 6
autoparal 1

acell 1 1 1 angstrom
 +4.7440200000  +0.0000000000  +0.0000000000 
 +0.0000000000  +4.9204393662  +0.0000000000 
 +0.0000000000  +0.0000000000 +15.0000000000 

ntypat 1
znucl  31

natom 4
typat 1 1 1 1
 +0.0000000000  +1.9081898149  +5.2271844041 
 +0.0000000000  +4.3684094980  +6.4204537083 
 +2.3720100000  +0.5520298682  +5.2271844041 
 +2.3720100000  +3.0122495508  +6.4204537083

ecut   60

nband  40

kptopt 1
ngkpt  32 32 1 
nshiftk 1
shiftk 0.0  0.0  0.0

nstep 500 
toldfe 1.0d-8
iscf 7
occopt 3
tsmear 0.01
#iprcel 45
Thank you very much for the attention.
Best regards, Mikhail

Re: Failing to relax a 2D structure

Posted: Wed Jan 29, 2020 6:05 pm
by MasoudMS
Hi Mikhail
check your shiftk and use optforces and nbdbuf keyword keywords. And check your pseudo potentials files.
Best regards

Re: Failing to relax a 2D structure

Posted: Sun Feb 09, 2020 12:00 am
by ebousquet
Dear Mikhail,
Can we see how bad is your convergence (from grep ETOT outputfile, for example)?
Also, what about if you start to relax the internal positions only?

Re: Failing to relax a 2D structure

Posted: Tue Mar 17, 2020 1:53 pm
Thank you all for your help.
I translated my vectors to angstroms manually, and switched to reduced atomic coordinates.
That fixed the problem.