Dear all users,
I am currently trying to relax a methylammonium lead iodide CH3NH3PbI3
structure which has tetragonal structure I4/mcm. Thus, in my input file, I
select ibrav = 7 (body centred teragonal). However, as I visualise the input
and output on Xcrysden, the unit cell becomes orthorhombic. Why is that?
&CONTROL
title = 'MAPI' ,
calculation = 'relax' ,
restart_mode = 'from_scratch' ,
outdir = './' ,
pseudo_dir = './' ,
prefix = 'CH3NH3PbI3' ,
/
&SYSTEM
ibrav = 7,
A = 8.83920,
C = 12.6948,
nat = 12,
ntyp = 5,
ecutwfc = 80 ,
ecutrho = 800,
/
&ELECTRONS
electron_maxstep = 5000 ,
conv_thr = 1.0d-6 ,
mixing_beta = 0.3 ,
/
&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 0.000000000 0.000000000 0.500000000
I 0.000000000 0.000000000 0.250000000
I 0.294200000 0.205800000 0.500000000
I -0.294200000 -0.207600000 0.500000000
C 0.544000000 0.921000000 0.784000000
H 0.609200000 1.002100000 0.769900000
H 0.557300000 0.845500000 0.724600000
H 0.551500000 0.875200000 0.864300000
N 0.389000000 0.987000000 0.767000000
H 0.324700000 0.913900000 0.730300000
H 0.381400000 1.068100000 0.734300000
H 0.339300000 0.990800000 0.831000000
K_POINTS automatic
1 1 1 0 0 0
Thank you all.
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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