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 yun.w...@griffith.edu.au<mailto:yun.w...@griffith.edu.au> https://experts.griffith.edu.au/academic/yun.wang Griffith University - CRICOS Provider Number 00233E PRIVILEGED - PRIVATE AND CONFIDENTIAL ________________________________ From: users <users-boun...@lists.quantum-espresso.org> on behalf of Chan, Edmund <thc...@exeter.ac.uk> Sent: Saturday, November 17, 2018 8:40:02 AM To: users@lists.quantum-espresso.org 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: thc...@exeter.ac.uk<mailto:thc...@exeter.ac.uk> LinkedIn: https://uk.linkedin.com/in/edmundchan1<https://uk.linkedin.com/in/edmundchan1> [uoe] [cid:image002.gif@01D2F1A2.9AF74CE0]
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