[QE-users] Convergence problem
amrendrak at rrcat.gov.in
amrendrak at rrcat.gov.in
Mon Aug 31 06:58:15 CEST 2026
Hi Akash,
I noticed multiple issues with your input file:
* etot_conv_thr = 1.0d-06 is too strict for a structural relaxation
and is set equal to the SCF convergence threshold. You can relax this
criterion to the default value (around (10^{-4}) Ry), or at most
(10^{-5}) Ry. I suggest trying (10^{-4}) first.
*
Is your system an insulator? If not, you should change
occupations = 'fixed'
to
occupations = 'smearing'
and choose an appropriate smearing scheme and width. * Do not mix
different types of pseudopotentials. Use either all PAW or all ultrasoft
pseudopotentials from the same library to ensure consistency and
reliable results.
Make these changes and see if you still encounter any errors.
Best,
Amrendra
SRF, HBNI-RRCAT
On 2026-08-29 10:43, Akash Saxena via users wrote:
> Dear all users,etot_conv_thr = 1.0000000000d-06
>
> Warm Greetings!
>
> I have been calculating the formation energy for the double-cation
> perovskite system, FA(1-x)Cs(x)PbI3. I have taken x to be 0.125, 0.25,
> 0.375, 0.5, 0.625, 0.75, 0.875, and 1.
>
> Out of these compositions, x=0.75 variable-cell relaxation calculation
> is not converging. I am sharing my input file below:-
>
> &CONTROL
> calculation = 'vc-relax'
> etot_conv_thr = 1.0000000000d-06
> forc_conv_thr = 1.0000000000d-03
> prefix = 'facspbi3'
> tprnfor = .true.
> tstress = .true.
> nstep = 200
> verbosity = 'high'
> pseudo_dir = '/home/pmlab/akashsaxena/fapi/facspbi3/pseudopot'
> outdir = '/home/pmlab/akashsaxena/fapi/facspbi3/0.75/lda/outdir_1'
> /
> &SYSTEM
> degauss = 2.0000000000d-02
> ecutwfc = 6.0000000000d+01
> ibrav = 0
> nat = 54
> nosym = .false.
> ntyp = 6
> occupations = 'fixed'
> smearing = 'gaussian'
> /
> &ELECTRONS
> conv_thr = 1.0000000000d-06
> electron_maxstep = 200
> diagonalization = 'cg'
> /
> &IONS
> ion_dynamics = 'bfgs'
> /
> &CELL
> cell_dynamics = 'bfgs'
> /
> ATOMIC_SPECIES
> Cs 132.905 Cs_pbe_v1.uspp.F.UPF
> C 12.0107 C.pbe-n-kjpaw_psl.1.0.0.UPF
> H 1.00794 H.pbe-rrkjus_psl.1.0.0.UPF
> I 126.90447 I.pbe-n-kjpaw_psl.0.2.UPF
> N 14.0067 N.pbe-n-radius_5.UPF
> Pb 207.2 Pb.pbe-dn-kjpaw_psl.0.2.2.UPF
> ATOMIC_POSITIONS crystal
> H 0.7500000000 0.3734180000 0.7500000000
> H 0.7500000000 0.8734180000 0.2500000000
> H 0.9020890000 0.2876760000 0.7500000000
> H 0.9020890000 0.7876760000 0.2500000000
> H 0.8486280000 0.1624660000 0.7500000000
> H 0.8486280000 0.6624660000 0.2500000000
> H 0.6513720000 0.1624660000 0.7500000000
> H 0.6513720000 0.6624660000 0.2500000000
> H 0.5979110000 0.2876760000 0.7500000000
> H 0.5979110000 0.7876760000 0.2500000000
> Pb 0.0000000000 0.4927880000 0.0000000000
> Pb 0.0000000000 0.4927880000 0.5000000000
> Pb 0.0000000000 0.9927880000 0.0000000000
> Pb 0.0000000000 0.9927880000 0.5000000000
> Pb 0.5000000000 0.4927880000 0.0000000000
> Pb 0.5000000000 0.4927880000 0.5000000000
> Pb 0.5000000000 0.9927880000 0.0000000000
> Pb 0.5000000000 0.9927880000 0.5000000000
> C 0.7500000000 0.2881400000 0.7500000000
> C 0.7500000000 0.7881400000 0.2500000000
> I 0.2500000000 0.4986690000 0.0000000000
> I 0.2500000000 0.4986690000 0.5000000000
> I 0.2500000000 0.9986690000 0.0000000000
> I 0.2500000000 0.9986690000 0.5000000000
> I 0.7500000000 0.4986690000 0.0000000000
> I 0.7500000000 0.4986690000 0.5000000000
> I 0.7500000000 0.9986690000 0.0000000000
> I 0.7500000000 0.9986690000 0.5000000000
> I 0.0000000000 0.2420610000 0.0000000000
> I 0.0000000000 0.2420610000 0.5000000000
> I 0.0000000000 0.7420610000 0.0000000000
> I 0.0000000000 0.7420610000 0.5000000000
> I 0.5000000000 0.2420610000 0.0000000000
> I 0.5000000000 0.2420610000 0.5000000000
> I 0.5000000000 0.7420610000 0.0000000000
> I 0.5000000000 0.7420610000 0.5000000000
> I 0.0000000000 0.4848850000 0.2500000000
> I 0.0000000000 0.4848850000 0.7500000000
> I 0.0000000000 0.9848850000 0.2500000000
> I 0.0000000000 0.9848850000 0.7500000000
> I 0.5000000000 0.4848850000 0.2500000000
> I 0.5000000000 0.4848850000 0.7500000000
> I 0.5000000000 0.9848850000 0.2500000000
> I 0.5000000000 0.9848850000 0.7500000000
> N 0.8388620000 0.2415790000 0.7500000000
> N 0.8388620000 0.7415790000 0.2500000000
> N 0.6611370000 0.2415790000 0.7500000000
> N 0.6611370000 0.7415790000 0.2500000000
> Cs 0.2500010000 0.7845050000 0.7500000000
> Cs 0.7500000000 0.2881400000 0.2500000000
> Cs 0.2500000000 0.2881400000 0.2500000000
> Cs 0.7500000000 0.7881400000 0.7500000000
> Cs 0.2500000000 0.2881400000 0.7500000000
> Cs 0.2500000000 0.7881400000 0.2500000000
> K_POINTS automatic
> 3 3 3 0 0 0
> CELL_PARAMETERS angstrom
> 13.1578080000 0.0000000000 0.0000000000
> 0.0000000000 12.7973780000 0.0000000000
> 0.0000000000 0.0000000000 13.1185190000
>
> In the output file, a large value for " negative_rho " is repeatedly
> reported, following which the program reports that the eigenvalues have
> not converged. I have attached a screenshot of the end of the output
> file to this email.
> Could anyone suggest where I am going wrong in the input file?
>
> Regards
>
> Akash, Ph.D. Scholar, IIT Bombay.
> _______________________________________________________________________________
> The Quantum ESPRESSO Foundation stands in solidarity with all civilians
> worldwide who are victims of terrorism, military aggression, and
> indiscriminate warfare.
> --------------------------------------------------------------------------------
> Quantum ESPRESSO is supported by MaX (www.max-centre.eu [1])
> users mailing list users at lists.quantum-espresso.org
> https://lists.quantum-espresso.org/mailman/listinfo/users
Links:
------
[1] http://www.max-centre.eu
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.quantum-espresso.org/pipermail/users/attachments/20260831/60f02a7f/attachment.html>
More information about the users
mailing list