[Pw_forum] Mo pseudopotential
mgtmentink@lbl.gov
mgtmentink at lbl.gov
Wed Mar 27 01:54:01 CET 2013
----- Reply message -----
From: "Ary Junior" <aryjunior at gmail.com>
To: "PWSCF Forum" <pw_forum at pwscf.org>
Subject: [Pw_forum] Mo pseudopotential
Date: Tue, Mar 26, 2013 2:38 pm
Dear all,
I was looking for a PBE USPP for molybdenum and checked that the .UPF files available in the QE website are the ones provided in pslibrary 0.2... So, based in the input file I created a test for the Mo.pbe-spn-rrkjus_psl.0.2.UPF file like this:
&input
title='Mo',
zed=42.0,
rel=1,
config='[Kr] 4d5.0 5s1 5p0',
iswitch=2,
dft='PBE',
rlderiv=2.93, eminld=-3.0, emaxld=3.0, deld=0.01, nld=3
/
&test
file_pseudo='Mo.pbe-spn-rrkjus_psl.0.2.UPF',
nconf=1,
configts(1)='4d5.0 5s1 5p0',
ecutmin=50, ecutmax=200, decut=50
/
Besides some warnings after the "All-electron run" section, the difference between the AE and the PS eigenvalues are zero and it is ok...
n l nl e AE (Ry) e PS (Ry) De AE-PS (Ry)
3 2 4D 1( 5.00) -0.27582 -0.27582 0.00000
1 0 5S 1( 1.00) -0.30033 -0.30033 0.00000
2 1 5P 1( 0.00) -0.07669 -0.07669 0.00000
However, when compare these eigenvalues with an atomic calculation using the spherical Bessel functions I got a weird result, even with a high cutoff energy:
Cutoff (Ry) : 200.0
N = 1 N = 2 N = 3
E(L=0) = -23.1157 Ry -13.3019 Ry -9.0812 Ry
E(L=1) = -20.7569 Ry -11.9179 Ry -7.7609 Ry
E(L=2) = -17.0812 Ry -9.9089 Ry -6.4930 Ry
Moreover, the AE vs PS logarithmic derivatives are quite discrepant, even at lower r values... The point is that after analyzing the shape of the AE orbitals I couldn't understand the so low rcut values in the pslibrary input file in both versions, 0.2 and 0.3... I have done the same test for other PBE USPPs available in the QE website like Ni.pbe-n-rrkjus_psl.0.1.UPF, O.pbe-n-rrkjus_psl.0.1.UPF and S.pbe-n-rrkjus_psl.0.1.UPF and they are fine... So, I tried to reset the input file with radii more compatible with the AE wavefunctions in my conception, besides change the core corrections like this:
&input
title='Mo',
prefix='Mo',
zed=42.0,
config='[Kr] 5s1 4d5 5p0',
iswitch=3,
dft='PBE',
rlderiv=2.93, eminld=-3.0, emaxld=3.0, deld=0.01, nld=3,
/
&inputp
pseudotype=3,
file_pseudopw='Mo.PBE-spn-rrkjus_aryjr.UPF',
author='ADC',
lloc=-1,
rcloc=3.2,
which_augfun='PSQ',
rmatch_augfun=1.3,
nlcc=.true.,
new_core_ps=.true.,
rcore=1.0,
tm=.true.
/
6
5S 1 0 1.00 0.00 2.70 3.30 0.0
5S 1 0 0.00 7.00 2.50 3.30 0.0
5P 2 1 0.00 0.00 3.20 3.30 0.0
5P 2 1 0.00 7.00 3.20 3.30 0.0
4D 3 2 5.00 0.00 1.50 1.70 0.0
4D 3 2 0.00 -0.30 0.70 1.70 0.0
Then, I think that everything is fine with the AE and the PS eigenvalues:
n l nl e AE (Ry) e PS (Ry) De AE-PS (Ry)
1 0 5S 1( 1.00) -0.30033 -0.30033 0.00000
3 2 4D 1( 5.00) -0.27582 -0.27582 0.00000
2 1 5P 1( 0.00) -0.07669 -0.07669 -0.00000
And after compare these eigenvalues with an atomic calculation using the spherical Bessel functions again, things look better now:
Cutoff (Ry) : 50.0
N = 1 N = 2 N = 3
E(L=0) = -0.3002 Ry -0.0021 Ry 0.0380 Ry
E(L=1) = -0.0766 Ry 0.0213 Ry 0.0681 Ry
E(L=2) = -0.2681 Ry 0.0313 Ry 0.0692 Ry
Cutoff (Ry) : 200.0
N = 1 N = 2 N = 3
E(L=0) = -0.3002 Ry -0.0021 Ry 0.0380 Ry
E(L=1) = -0.0766 Ry 0.0213 Ry 0.0681 Ry
E(L=2) = -0.2683 Ry 0.0313 Ry 0.0692 Ry
The AE vs PS logarithmic derivatives are being well reproduced in energies lower than 1 Ry.... I also tested chemical states like the ionized Mo4+ and Mo6+, and the results are listed below:
1 0 5S 1( 1.00) -0.30033 -0.30033 0.00000
3 2 4D 1( 5.00) -0.27582 -0.27582 0.00000
2 1 5P 1( 0.00) -0.07669 -0.07669 -0.00000
Etot = -8097.243530 Ry, -4048.621765 Ha, -110168.600949 eV
Etotps = -32.753518 Ry, -16.376759 Ha, -445.634282 eV
1 0 5S 1( 0.00) -2.69065 -2.78173 0.09108
3 2 4D 1( 2.00) -3.40343 -3.51010 0.10667
2 1 5P 1( 0.00) -2.17762 -2.27343 0.09581
dEtot_ae = 6.511981 Ry
dEtot_ps = 6.625031 Ry, Delta E= -0.113050 Ry
1 0 5S 1( 0.00) -4.30796 -4.58873 0.28077
3 2 4D 1( 0.00) -5.60739 -5.87530 0.26791
2 1 5P 1( 0.00) -3.66423 -3.99180 0.32756
dEtot_ae = 15.474602 Ry
dEtot_ps = 15.954369 Ry, Delta E= -0.479767 Ry
My question: is my procedure described above wrong? Study and understand the generation of PSPs is not easy for me and I'm trying to learn it grounded in some textbooks as well as some documents spread on the internet and of course the input files provided in the pslibrary project. But this PBE USPP for molybdenum made me a little bit confused. I tested both in a MoS2 unit cell with PBE-D and the cell volume as well as the interatomic distances are fine if compared with the experiments, with differences lower than 3%... One more question: how can I improve the result for the Mo4+ and Mo6+ ionized states?
Thank you very much!
Ary Junior
Doctoral Student
Chemistry Department
Universidade Federal de Juiz de Fora - MG - Brasil
--
http://lattes.cnpq.br/8221674673413336
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