Dear QE Users,
Greetings,
I have been studying QE for half a year, currently I am working on optimizing
the crystal structure of gelatin molecule. The initial coordinates was obtained
from a protein ‘.pdb’ file of gelatin. I do not know whether it is the best
configuration so that I use QE to run the vc-relax.
The problem I have come across is that the ‘forc_conv_thr’ is hard to be
achieved, when I plot the history of force, I can see after a certain number
of iterations, the total force would vibrate around a certain value(~1e-2) a
little bit. Theoretically the total force should be decreasing to 0, I have
tried to adjust the input parameters, like ecutwfc(50~150), mixing_beta(0.1 ~
0.7), bfgs to damp, but not effective. Please give any suggestions on what
should I do?
Thanks a lot and Best regards.
Chunhua
The input can be seen below:
&CONTROL
calculation = "vc-relax"
forc_conv_thr = 1.00000e-06
etot_conv_thr = 1.00000e-04
max_seconds = 28800
outdir='./outdir'
pseudo_dir = "/home/chunhua/QuantumEspresso/PAW_precision_pseudos"
restart_mode = "from_scratch"
nstep=100
/
&SYSTEM
degauss = 1.00000e-02
ecutrho = 5.00000e+02
ecutwfc = 1.00000e+02
ibrav = 0
nat = 217
ntyp = 4
occupations = "smearing"
smearing = "gaussian"
/
&ELECTRONS
conv_thr = 1.00000e-04
electron_maxstep = 200
mixing_beta = 1.00000e-01
startingpot = "atomic"
startingwfc = "atomic+random"
/
&IONS
ion_dynamics = "bfgs"
/
&CELL
cell_dofree = "all"
cell_dynamics = "bfgs"
press_conv_thr = 5.00000e-01
/
K_POINTS {gamma}
CELL_PARAMETERS {angstrom}
32.039000 0.000000 0.000000
0.000000 30.039000 0.000000
0.000000 0.000000 50.039000
ATOMIC_SPECIES
O 15.99940 O.pbe-n-kjpaw_psl.1.0.0.UPF
N 14.00674 N.pbe-n-kjpaw_psl.1.0.0.UPF
H 1.00794 H.pbe-kjpaw_psl.1.0.0.UPF
C 12.01070 C.pbe-n-kjpaw_psl.1.0.0.UPF
ATOMIC_POSITIONS {angstrom}
N 7.659071 9.660491 38.488224
H 7.708071 8.734491 38.052224
C 6.804071 9.663491 39.674224
H 6.853071 10.650491 40.137224
C 7.465071 8.662491 40.595224
O 8.658071 8.812491 40.838224
C 5.336071 9.344491 39.352224
H 4.737071 9.431491 40.259224
……………………….
……………………….
-----------------------------------------------------------
Chunhua Ying
Ph.D. Student
School of Mechanical and Materials Engineering
Washington State University
Engineering Laboratory Building, 105
900 NE College Ave, Pullman, WA 99164
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