[Pw_forum] Non converging neb calculation
Masoud
masoudnahali at gmail.com
Mon Nov 19 12:59:36 CET 2012
Dear Korir
First of all you are going from A to B !! but A and B are too different
from each other. For a TS structure only few atoms change their locations
compared to the reactant or product. Also are you sure that you have
already set the atomic numbers the same as each other for A and B ?
you can fix 80-90 percent of atoms during the NEB calculation for the first
steps also you should use "no-CI" and then "auto".
Oxygen is a spin polarized atom !! why didn't you consider that ? you need
to use nspin=2 and a value for starting_magnetization.
In some cases 28 for the cutoff is not sufficient.
Overall I think that the first step to figure it out is checking your
structure and then the details that I have mentioned.
I hope it helps.
Best Wishes, m
----------------------------------------
Masoud Nahali
SUT
masoud.nahali at gmail.com
alum.sharif.edu/~m_nahali <http://alum.sharif.edu/%7Em_nahali>
Date: Sun, 18 Nov 2012 23:38:07 +0100
Korir wrote:
Dear QE community,
I am interested in studying oxygen vacancy diffusion in ZnO and for this
reason I performed neb calculation using the input attached, but for some
reasons I don't understand, the system does not converge even though the
initial and final states optimized beforehand. Furthermore, the choice of
vacancy position were made in such that they correspond to first neighbor
oxygen atoms in ZnO. Attached are input and output files.
Kindly assist in addressing this problem.
Regards
Korir Kiprono
Polytechnic of Turin
Italy
BEGIN
BEGIN_PATH_INPUT
&PATH
restart_mode = 'from_scratch'
string_method = 'neb',
nstep_path = 400,
ds = 1.D0,
opt_scheme = "broyden",
num_of_images = 11,
k_max = 0.1D0,
k_min = 0.05D0,
first_last_opt = .true.,
CI_scheme = "auto",
path_thr = 0.05D0,
/
END_PATH_INPUT
BEGIN_ENGINE_INPUT
&CONTROL
prefix = "ZnO_Ovac",
outdir = "./tmp",
pseudo_dir = "./",
/
&SYSTEM
ibrav = 0,
celldm(1) = 12.42108529,
nat = 31,
ntyp = 2,
ecutwfc = 28.0D0,
ecutrho = 280.0D0,
occupations ='smearing',
smearing ='gaussian',
degauss = 0.005,
/
&ELECTRONS
conv_thr = 1.D-8,
mixing_beta = 0.3D0,
/
&IONS
/
ATOMIC_SPECIES
Zn 65.39 Zn.pbe-van_ak.UPF
O 15.99 O.pbe-van_ak.UPF
BEGIN_POSITIONS
FIRST_IMAGE
ATOMIC_POSITIONS {angstrom }
Zn 0.000000000 0.000000000 -0.000901300
O 0.000000000 0.000000000 1.982166429
Zn 1.618166296 0.934248744 2.660882286
O 1.587537112 0.916564976 4.668341083
Zn 0.000000000 0.000000000 5.549324230
Zn 1.510731530 0.872221253 7.785147076
O 1.614761747 0.932283127 9.789420866
Zn -1.647149135 2.813900718 -0.034865746
O -1.647131851 2.813910697 1.979064959
Zn 0.000000002 3.764882713 2.578931174
O 0.000000002 3.764882713 4.586148646
Zn -1.624551499 2.826947470 5.242777187
O -1.641528837 2.817145598 7.246106096
Zn 0.000000002 3.764882713 7.873821255
O 0.000000002 3.764882713 9.870733921
Zn 3.260484073 0.019522635 -0.034865746
O 3.260484073 0.019502678 1.979064959
Zn 4.902801854 0.934248744 2.660882286
O 4.933431038 0.916564976 4.668341083
Zn 3.260484073 -0.006570867 5.242777187
O 3.260484073 0.013032875 7.246106096
Zn 5.010236620 0.872221253 7.785147076
O 4.906206403 0.932283127 9.789420866
Zn 1.647149135 2.813900718 -0.034865746
O 1.647131851 2.813910697 1.979064959
Zn 3.260484075 3.778826580 2.660882286
O 3.260484075 3.814194115 4.668341083
Zn 1.624551499 2.826947470 5.242777187
O 1.641528837 2.817145598 7.246106096
Zn 3.260484075 3.902881561 7.785147076
O 3.260484075 3.782757814 9.789420866
LAST_IMAGE
ATOMIC_POSITIONS {angstrom }
Zn 0.119469042 0.068975484 -0.085296951
O 0.015207179 0.008779869 1.918954244
Zn 1.630247715 0.941223955 2.620686267
O 1.630247715 0.941223955 4.604032865
Zn 0.012421523 0.007171570 5.284174983
O 0.042886882 0.024760753 7.291900841
Zn 1.630247715 0.941223955 8.172918735
Zn -1.630247713 2.823671869 0.005029795
O -1.630247713 2.823671869 2.001908162
Zn 0.017145427 3.774794739 2.588903716
O 0.016953247 3.774683784 4.602875645
Zn -1.630247713 2.823671869 5.202337904
O -1.630247713 2.823671869 7.209073955
Zn -0.005796021 3.761549488 7.866297372
O 0.010971356 3.771230138 9.869611927
Zn 3.141026385 0.068975484 -0.085296951
O 3.245288248 0.008779869 1.918954244
Zn 4.890743142 0.921426124 2.588903716
O 4.890743142 0.921648034 4.602875645
Zn 3.248073903 0.007171570 5.284174983
O 3.217608545 0.024760753 7.291900841
Zn 4.890743142 0.947916625 7.866297372
O 4.890743142 0.928555326 9.869611927
Zn 1.630247713 2.685720902 -0.085296951
O 1.630247713 2.806112131 1.918954244
Zn 3.243350004 3.774794739 2.588903716
O 3.243542184 3.774683784 4.602875645
Zn 1.630247713 2.809328729 5.284174983
O 1.630247713 2.774150362 7.291900841
Zn 3.266291452 3.761549488 7.866297372
O 3.249524075 3.771230138 9.869611927
END_POSITIONS
K_POINTS { gamma }
CELL_PARAMETERS (alat)
0.990204093 0.000000000 0.000000000
-0.495102046 0.857541899 0.000000000
0.000000000 0.000000000 1.593439130
END_ENGINE_INPUT
END
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