other issue is that celldm(3) is the ratio between c axis length and
celldm(1), thus you should consider values for celldm(3) between
10./celldm(1) and 16/celldm(1).
On 17/11/18 04:08, Yun Wang wrote:
Dear Edmund,
The (1x1x1) k-point mesh is not good enough to get the reliable data
for your system.
You may also need to consider the van der Waals correction due to the
existence of the large atoms.
Best regards,
Yun
*Dr Yun Wang | Senior Lecturer PhD*
*Centre for Clean Environment and Energy | **School of Environment &
Science*
*Griffith University****| Gold Coast campus | QLD 4215 | G24 Room 3.36*
*T +61 7 5552 8358 | email **[email protected]*
<mailto:[email protected]>
https://experts.griffith.edu.au/academic/yun.wang
Griffith University - CRICOS Provider Number 00233E
PRIVILEGED - PRIVATE AND CONFIDENTIAL
------------------------------------------------------------------------
*From:* users <[email protected]> on behalf of
Chan, Edmund <[email protected]>
*Sent:* Saturday, November 17, 2018 8:40:02 AM
*To:* [email protected]
*Subject:* [QE-users] Help: How to optimise lattice c parameter in scf
calculation
Dear all,
I am currently working on a CH3NH3PbI3 I4/mcm tetragonal structure. I
would like to optimise the lattice parameter c using scf calculation
after optimising geometry using relax calculation. I tried to fix
celldm(1) and changes celldm(3) so that lattice parameter c ranges
10.5-13.5 (true value should be about 12.6, sum of Pb-I-Pb-I-Pb)
However, calculations still don't show min energy within the range.
still decreasing when celldm(3) keeps decreasing.
Any solution?
Thanks a lot in advance.
#!/bin/sh
####################################################################
#
# define the following variables according to your needs
#
# outdir=temporary_directory_for_large_files
# pseudo_dir=directory_where_pp-files_are_kept
# espresso_dir=top_directory_of_espresso_package
# code : sh run_si_eos
####################################################################
rm -f MAPI_scf.out MAPI.etot_vs_alat
touch MAPI.etot_vs_alat
for alat in 1.2572090494 1.2721758238 1.2871425982 1.3021093726
1.317076147 1.3320429214 1.3470096958 1.3619764701 1.3769432445
1.3919100189 1.4068767933 1.4218435677 1.4368103421 1.4517771165
1.4667438909 1.4817106653 1.4966774397 ; do
# self-consistent calculation
cat > MAPI_scf.in << EOF
&control
calculation='scf',
restart_mode='from_scratch',
prefix='MAPI',
pseudo_dir = '/home/edmund/Quantum-Espresso/pseudo/SSSP_Acc/PBESOL/',
outdir='/home/edmund/Quantum-Espresso/Tutorial/tmp/'
/
&system
ibrav= 6, celldm(1) = 16.703665958 , celldm(3) = $alat , nat= 12, ntyp= 5,
ecutwfc = 70,
/
&electrons
electron_maxstep = 5000,
mixing_beta = 0.3,
conv_thr = 1.0d-6,
/
&ions
ion_dynamics="bfgs",
/
ATOMIC_SPECIES
C 12.01070 c_pbesol_v1.2.uspp.F.UPF
H 1.00794 H.pbesol-rrkjus_psl.0.1.UPF
N 14.00670 N.pbesol-theos.UPF
Pb 207.20000 Pb.pbesol-dn-kjpaw_psl.0.2.2.UPF
I 126.90450 i_pbesol_v1.uspp.F.UPF
ATOMIC_POSITIONS (alat)
Pb -0.060250864 0.119717291 0.415558090
I -0.007273724 -0.001439398 0.113823814
I 0.267082396 0.174145023 0.503051646
I -0.111188287 -0.164962141 0.584095713
C 0.535192046 0.927588487 0.796494424
H 0.581905016 1.042275920 0.809533204
H 0.580744698 0.877063608 0.692556190
H 0.570638845 0.855097719 0.891131917
N 0.366943691 0.939129847 0.789578969
H 0.318073687 0.834961464 0.773620510
H 0.328759438 1.011781981 0.698437223
H 0.325773058 0.986440200 0.887518302
K_POINTS automatic
1 1 1 0 0 0
EOF
pw.x < MAPI_scf.in > MAPI_scf.out
# extract Etot from output
etot=`grep -e ! MAPI_scf.out | awk '{print $(NF-1)}'`
echo $alat $etot >> MAPI.etot_vs_alat
done
Kind regards,
Edmund Chan
________________________________________________
*Edmund Chan*
PhD Renewable Energy Student
Environment & Sustainablity Institute
College of Engineering, Mathematics and Physical Sciences
University of Exeter, Penryn Campus
Penryn, Cornwall
United Kingdom
TR10 9FE
/Tel:/+44 (0)7455 235 701
/Email:/[email protected] <mailto:[email protected]>
/LinkedIn: https://uk.linkedin.com/in/edmundchan1///
uoe//
cid:[email protected]
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