[Pw_forum] slab relaxtion in external field can't reach convergence
Liping YU
lyu7 at ncsu.edu
Sat Nov 19 05:29:01 CET 2005
Dear PWSCF users,
I am trying to use pw.x (version 2.1.5) relax a slab in a fixed external
electric field. I do this by setting following variables in the input
file for 'relax' calculation.
>> tefield = .true., edir = 3, eamp = 0.02, emaxpos = 0.00,
eopreg = 0.01<<
(note: the slab is centered in the middle of the supercell and
(thickness) occupies 3/5 in z-direction.)
My problem is that: the program always finishes running after < 5 bfgs
steps without any convergences (the atom positions didn't change and
forces on them were still very large). But if I set 'eamp=0.0' and leave
all other variables unchanged in the same input file(which is the case I
think for applying zero field) , it works well and structure is relaxed
to where I want. Do you have any idea on this? Many thanks in advance!
liping
----------------------------
my input file:
----------------------------
&CONTROL
title = 'relax TiO2 terminated [001] te-PbTiO3
slab 7layers+4vacs' ,
calculation = 'relax' ,
restart_mode = 'from_scratch' ,
outdir = './tmp/' ,
pseudo_dir = '../../pseudo/' ,
prefix = 'te-pb.slab' ,
etot_conv_thr = 1.0D-4,
forc_conv_thr = 5.0D-4,
nstep = 250,
tstress = .true. ,
tprnfor = .true. ,
tefield = .true. ,
dt = 120 ,
/
&SYSTEM
ibrav = 6,
celldm(1) = 7.284856,
celldm(3) = 5.2010,
nat = 18,
ntyp = 3,
occupations = 'smearing',
smearing = 'gaussian',
degauss = 0.01,
ecutwfc = 30.0,
ecutrho = 250.0,
edir = 3,
emaxpos = 0.00,
eopreg = 0.01,
eamp = 0.01,
nosym = .true.
/
&ELECTRONS
electron_maxstep = 100,
diagonalization = 'cg' ,
mixing_beta = 0.1,
conv_thr = 1.D-8,
/
&IONS
upscale=10.d0
/
ATOMIC_SPECIES
Pb 207.2000 Pb.pz-d-van.UPF
Ti 47.86700 022-Ti-ca-sp-vgrp.uspp.UPF
O 16.00000 008-O-ca--vgrp.uspp.UPF
ATOMIC_POSITIONS crystal
O 0.5 0.0 0.78039 0 0 1
O 0.0 0.5 0.78039 0 0 1
Ti 0.5 0.5 0.79368 0 0 1
O 0.5 0.5 0.68299 0 0 1
Pb 0.0 0.0 0.70000 0 0 1
O 0.5 0.0 0.58039 0 0 1
O 0.0 0.5 0.58039 0 0 1
Ti 0.5 0.5 0.59368 0 0 1
O 0.5 0.5 0.48299 0 0 1
Pb 0.0 0.0 0.50000 0 0 0
O 0.5 0.0 0.38039 0 0 1
O 0.0 0.5 0.38039 0 0 1
Ti 0.5 0.5 0.39368 0 0 1
O 0.5 0.5 0.28299 0 0 1
Pb 0.0 0.0 0.30000 0 0 1
O 0.5 0.0 0.18039 0 0 1
O 0.0 0.5 0.18039 0 0 1
Ti 0.5 0.5 0.19368 0 0 1
K_POINTS automatic
5 5 1 0 0 0
------------------
part of output
-------------------
! total energy = -1180.25248656 ryd
estimated scf accuracy < 4.3E-09 ryd
band energy sum = -99.32162764 ryd
one-electron contribution = -3491.94140692 ryd
hartree contribution = 1812.19849675 ryd
xc contribution = -176.79463848 ryd
ewald contribution = 674.50015201 ryd
electric field correction = 1.79085470 ryd
correction for metals = -0.00594461 ryd
convergence has been achieved
Forces acting on atoms (Ry/au):
atom 1 type 3 force = 0.00000000 0.00000000 -0.00637085
atom 2 type 3 force = 0.00000000 0.00000000 -0.00637069
atom 3 type 2 force = 0.00000000 0.00000000 -0.06007066
atom 4 type 3 force = 0.00000000 0.00000000 0.01979378
atom 5 type 1 force = 0.00000000 0.00000000 0.09385845
atom 6 type 3 force = 0.00000000 0.00000000 -0.03255876
atom 7 type 3 force = 0.00000000 0.00000000 -0.03255858
atom 8 type 2 force = 0.00000000 0.00000000 0.00631018
atom 9 type 3 force = 0.00000000 0.00000000 -0.00570834
atom 10 type 1 force = 0.00000000 0.00000000 0.07250243
atom 11 type 3 force = 0.00000000 0.00000000 -0.03060398
atom 12 type 3 force = 0.00000000 0.00000000 -0.03060406
atom 13 type 2 force = 0.00000000 0.00000000 0.01326980
atom 14 type 3 force = 0.00000000 0.00000000 -0.02455655
atom 15 type 1 force = 0.00000000 0.00000000 0.05976386
atom 16 type 3 force = 0.00000000 0.00000000 -0.04895601
atom 17 type 3 force = 0.00000000 0.00000000 -0.04895608
atom 18 type 2 force = 0.00000000 -0.00000001 0.06181605
Total force = 0.172980 Total SCF correction = 0.000128
number of scf cycles = 4
number of bfgs steps = 1
energy old = -1182.1383466357 ryd
energy new = -1180.2524865583 ryd
CASE: energy_new > energy_old
new trust radius = 0.0000000000 bohr
bfgs converged in 4 scf cycles and 1 bfgs steps
End of BFGS geometry calculation
Final energy = -1182.1383466357 ryd
Saving the approximate inverse hessian
CELL_PARAMETERS (alat)
1.000000000 0.000000000 0.000000000
0.000000000 1.000000000 0.000000000
0.000000000 0.000000000 5.201000000
ATOMIC_POSITIONS (crystal)
O 0.500000000 0.000000000 0.780390000
O 0.000000000 0.500000000 0.780390000
Ti 0.500000000 0.500000000 0.793680000
O 0.500000000 0.500000000 0.682990000
Pb 0.000000000 0.000000000 0.700000000
O 0.500000000 0.000000000 0.580390000
O 0.000000000 0.500000000 0.580390000
Ti 0.500000000 0.500000000 0.593680000
O 0.500000000 0.500000000 0.482990000
Pb 0.000000000 0.000000000 0.500000000
O 0.500000000 0.000000000 0.380390000
O 0.000000000 0.500000000 0.380390000
Ti 0.500000000 0.500000000 0.393680000
O 0.500000000 0.500000000 0.282990000
Pb 0.000000000 0.000000000 0.300000000
O 0.500000000 0.000000000 0.180390000
O 0.000000000 0.500000000 0.180390000
Ti 0.500000000 0.500000000 0.193680000
Writing file te-pb.slab.sav for program phonon
PWSCF : 1h 7m CPU time
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