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<p>Dear Venkataramana</p>
<p>Try to decrease conv_thr below 1.0e-9 </p>
<p>It might be that the one you are looking for is a local minimum
with a small barrier; convergence threshold in &electrons is
quite high and your forces may be too inaccurate to stay around
the local minimum ( always supposing that your starting position
falls in the basin of such local minimum). <br>
</p>
<p>regards - pietro<br>
</p>
<br>
<div class="moz-cite-prefix">On 11/04/2018 07:49, Venkataramana
Imandi wrote:<br>
</div>
<blockquote type="cite"
cite="mid:CAEJJhnuBi+a_+3aansmnx=sXB7gCYiaZ++zSjSY8=fH0MAKF1A@mail.gmail.com">
<div dir="ltr">Dear QE users,<br clear="all">
<br>
Simulation cell parameters are same in the VASP and QE. In both
cases, simulation started from the same input structure.<br>
I am using 6.2.1 version of QE.<br>
QE: I used the BFGS for geometry optimization, Davidson
diagonalization for electronic scf and Pt(Pt.pbe-nd-rrkjus.UPF),
O(O.pbe-rrkjus.UPF).<br>
<br>
VASP: I used RMM-DIIS for geometry optimization, Davidson
diagaonalization or cg for electronic scf and
Pt(PW91-ultrasoft), O(PW91-ultrasoft).<br>
<br>
For information,<br>
I obtained all O_ad(O-adsorption) sites(top,bridge,hcp and fcc)
on pt-surface in the VASP. In VASP, I found interlayer
spacing(3rd and 2nd layer difference) varied +0.02 to +0.03
angstroms compared to initial structure.<br>
<br>
But in QE, I obtained all O_ad sites except bridge site on
Pt-surface.<br>
In QE, I found interlayer spacing(3rd and 2nd layer difference)
varied >+0.05 angstroms more compared to initital structure.<br>
<br>
Thus, I found more relaxed structure in QE compared to VASP.<br>
<br>
Any suggestions are greatly appreciated.<br>
<br>
My input file as follow.<br>
<br>
&control<br>
calculation='relax'<br>
restart_mode='from_scratch',<br>
pseudo_dir = '/home2/oth/ch18ipf01/pseudopotential2/',<br>
prefix='pto'<br>
tprnfor = .true.,<br>
nstep = 200<br>
/<br>
&system<br>
ibrav=0,<br>
nat=49,<br>
ntyp=2,<br>
! nspin = 2,<br>
! starting_magnetization(1)=0.7,<br>
ecutwfc = 32.0,<br>
ecutrho = 320.0,<br>
occupations='smearing',<br>
smearing='methfessel-paxton',<br>
degauss=0.02<br>
/<br>
&electrons<br>
diagonalization='cg'<br>
conv_thr = 1.0e-6<br>
mixing_beta = 0.3<br>
electron_maxstep = 1000<br>
/<br>
&ions<br>
ion_dynamics='bfgs',<br>
/<br>
ATOMIC_SPECIES<br>
Pt 195.084 Pt.pbe-nd-rrkjus.UPF<br>
O 15.999 O.pbe-rrkjus.UPF<br>
<br>
ATOMIC_POSITIONS {angstrom}<br>
O 4.83670 3.24076 9.895064 1 1 1<br>
Pt 7.7079 5.67952 7.91015 1 1 1<br>
Pt 6.36297 8.19933 7.98784 1 1 1<br>
Pt 4.91919 6.00109 8.19464 1 1 1<br>
Pt 3.48056 8.20502 7.98339 1 1 1<br>
Pt 2.13171 5.68297 7.90776 1 1 1<br>
Pt 0.69985 8.11366 7.9477 1 1 1<br>
Pt 7.78611 0.73129 7.94675 1 1 1<br>
Pt 6.42371 3.08952 8.08857 1 1 1<br>
Pt 4.92315 0.76409 7.92858 1 1 1<br>
Pt 3.41889 3.09455 8.08213 1 1 1<br>
Pt 2.05589 0.73846 7.94323 1 1 1<br>
Pt 0.69979 3.32663 7.96547 1 1 1<br>
Pt 6.29321 4.95311 5.73597 1 1 1<br>
Pt 7.73513 7.49799 5.63702 1 1 1<br>
Pt 3.54425 4.96152 5.72897 1 1 1<br>
Pt 4.92162 7.32106 5.7753 1 1 1<br>
Pt 0.69791 5.10582 5.63088 1 1 1<br>
Pt 2.10707 7.50605 5.63432 1 1 1<br>
Pt 6.32478 0.10848 5.63611 1 1 1<br>
Pt 7.70985 2.61906 5.72581 1 1 1<br>
Pt 3.51897 0.11648 5.63414 1 1 1<br>
Pt 4.92144 2.53817 5.67277 1 1 1<br>
Pt 0.69984 0.23217 5.59048 1 1 1<br>
Pt 2.13138 2.62752 5.72184 1 1 1<br>
Pt 6.32344 6.78474 3.44718 1 1 1<br>
Pt 7.7339 9.3212 3.38713 1 1 1<br>
Pt 3.51851 6.7929 3.44491 1 1 1<br>
Pt 4.9219 9.19308 3.42498 1 1 1<br>
Pt 0.6991 6.90045 3.3778 1 1 1<br>
Pt 2.10972 9.32712 3.38533 1 1 1<br>
Pt 6.33835 1.94543 3.42008 1 1 1<br>
Pt 7.72421 4.42937 3.42142 1 1 1<br>
Pt 3.50426 1.95276 3.41781 1 1 1<br>
Pt 4.92063 4.34401 3.43929 1 1 1<br>
Pt 0.6992 2.09004 3.40181 1 1 1<br>
Pt 2.11503 4.43554 3.41785 1 1 1<br>
Pt 7.73571 6.2569 1.1 0 0 0<br>
Pt 6.32857 8.69414 1.1 0 0 0<br>
Pt 4.92143 6.2569 1.1 0 0 0<br>
Pt 3.51428 8.69414 1.1 0 0 0<br>
Pt 2.10714 6.2569 1.1 0 0 0<br>
Pt 0.7 8.69414 1.1 0 0 0<br>
Pt 7.73571 1.38241 1.1 0 0 0<br>
Pt 6.32857 3.81966 1.1 0 0 0<br>
Pt 4.92143 1.38241 1.1 0 0 0<br>
Pt 3.51428 3.81966 1.1 0 0 0<br>
Pt 2.10714 1.38241 1.1 0 0 0<br>
Pt 0.7 3.81966 1.1 0 0 0<br>
<br>
K_POINTS {automatic}<br>
2 2 1 0 0 0<br>
CELL_PARAMETERS {angstrom}<br>
8.4428549700000008 0.0000000000000000 0.0000000000000000<br>
0.0000000000000000 9.7489691799999996 0.0000000000000000<br>
0.0000000000000000 0.0000000000000000 19.1916000000000011<br>
<br>
<br>
With best regards<br>
Venkataramana Imandi<br>
Postdoctoral fellow<br>
IIT Madras, India.<br>
<br>
<br>
<br>
</div>
<br>
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