[Pw_forum] Single Cell vs Super-Cell
Peter O Orondo wrote: > I am trying to calculate the chemical potential of H in a bunch of > metals. When I use a single cell, I get results that compare to > experiment. However, when I use a 2x2x2 super-cell, I expect to get a > more accurate result since the super-cell should model the physical > properties more accurately. However, the super-cell results don?t even > have the right shape. The results look rather random. > > Any insights into what could be wrong? hard to say. The fact that you get results that compare well to experiments doesn't imply that those results are correct. In simple metals, if you put one H atom per unit cell you simulate a hydride rather than H dissolved into a metal. If you increase the size of the supercell, you should notice that your results (e.g. the formation energy) converges to some value, which should be good for a isolated impurity. Convergence may be quite slow, though, depending upon what you calculate and in which system Paolo -- Paolo Giannozzi, Democritos and University of Udine, Italy
[Pw_forum] Bi - pseudopotential (fully relativistic)
Dear users, Searching the forum, a time ago I saw a discussion on how to generate a Bi PP (fully relativistic) (http://www.democritos.it/pipermail/pw_forum/2006-May/004181.html). I was wondering how that worked out, the PP is not listed on QE pseudopotentials database. I'm looking for that kind of a PP. Please publish it in the database or share it in some way. Thank you in advance. Vasse Chis Department of Physics University of Central Florida -- next part -- An HTML attachment was scrubbed... URL: http://www.democritos.it/pipermail/pw_forum/attachments/20100915/9ce9ba58/attachment.htm
[Pw_forum] Occupations in CP
Dear all,
I tried to perform CP-MD simulations moving
electrons beyond the highest KS state.
In theory, this can be done using
occupations='from_input'
and playing with the OCCUPATIONS card, using
a number of bands larger than half of the number
of electrons.
Here is an example for isolated H2 molecule:
# electron steepest-descent
calculation='cp',
restart_mode='from_scratch',
prefix='elsd2',
pseudo_dir='/home/lapenna/espresso_pseudo/',
outdir='/home/lapenna/deloc/H2/./tmp/',
ekin_conv_thr =1.e-06,
nstep=50, iprint=10, isave=100,
dt=2.0,
ndr=50, ndw=60,
/
ibrav= 1,
celldm(1)= 11,
nat=2, ntyp=1,
tot_charge=0.,
!nelec=2,
nspin=1, nbnd=2,
ecutwfc = 25.0, ecutrho = 250.0,
nr1b = 20, nr2b = 20, nr3b = 20,
!occupations='fixed',
occupations='from_input',
/
emass = 400.,
electron_dynamics = 'sd',
!electron_dynamics = 'damp',
orthogonalization = 'ortho',
ortho_max = 1000,
/
ion_dynamics = 'none',
ion_positions = 'from_input',
!ion_dynamics = 'damp',
/
ATOMIC_SPECIES
H 1.008 H.pbe-rrkjus.UPF
ATOMIC_POSITIONS {bohr}
H0.472420E+01 0.472438E+01 0.476847E+01
H0.472443E+01 0.472425E+01 0.619194E+01
OCCUPATIONS
0.0 2.0
In the output (QE-4.2) I read:
...
Wave Initialization: random initial wave-functions
Occupation number from init
nbnd = 2
0.00 0.00
...
Same occupation numbers every time they are printed,
inconsistently with the charge of the system that
is zero.
Continuing with the dynamics, the H2 dissociation occurs
as expected, while with occupations 2. 0. the correct
minimum is satisifed. Maybe the comparison between
different occupations in CP-MD is nonsense, but this is another
story.
Why the occupations are all zero beyond the last non-zero
from input?
Is it a safety measure preventing such hazardous experiments?
Also in this latter case, the measure does not work,
except in the case of a careful output reading...
PW prints occupations as in input.
Thank you in advance,
Giovanni
Giovanni La Penna - National research council (Cnr)
Institute for chemistry of organo-metallic compounds (Iccom)
via Madonna del Piano 10,
I-50019 Sesto Fiorentino, Firenze, Italy
tel.: +39 055 522-5264, fax: +39 055 522-5203
e-mail: glapenna at iccom.cnr.it - http://www.iccom.cnr.it/lapenna
skype: giovannilapenna
[Pw_forum] Re [8] : US-PP of Au
Dear Lorenzo Thank you to reply. It is always segmentation fault. My system is 3-atoms Au cluster. this cluster forms a chain of atoms but the calculations never finished because of segmentation fault. Dear Gabriele the work was completely don with kinetic-energy cutoff=32. Ry and charge density cutoff = 320. Ry . *Forces acting on atoms (Ry/au): atom 1 type 1 force =-0.9579 -0.95790. atom 2 type 1 force = 0.00013265 -0.36860. atom 3 type 1 force =-0.36860.000132650. Total force = 0.000237 Total SCF correction = 0.000290 SCF correction compared to forces is too large, reduce conv_thr bfgs converged in 24 scf cycles and 19 bfgs steps (criteria: energy < 0.10E-03, force < 0.10E-02) End of BFGS Geometry Optimization Final energy =-262.9046471560 Ry Begin final coordinates ATOMIC_POSITIONS (angstrom) Au 1.381049485 1.381049485 0.0 Au 3.868137287 -1.139186772 0.0 Au -1.139186772 3.868137287 0.0 End final coordinates* Best wishes. Reza.Shidpour Institute for Nanoscienec and Nanotechnology, SUT -- next part -- An HTML attachment was scrubbed... URL: http://www.democritos.it/pipermail/pw_forum/attachments/20100915/97843a52/attachment.htm
[Pw_forum] problems with converge of geometric optimization
I am trying to calculate an H-center in CaF2, and I am having trouble with the geometry optimization. I have tried adjusting various parameters such as ion dynamics, trust radius, convergence tresholds, but it seems that convergence cannot be improved. Using bfgs I always get the following error: %% from bfgs : error # 1 bfgs history already reset at previous step %% Alternatively the electonic convergence gets extremely slow. In addition, no matter what parameters I adjust the total forces in the system never converge, e.g. Total force = 0.026394 Total SCF correction = 0.000314 Total force = 0.018379 Total SCF correction = 0.000282 Total force = 0.018824 Total SCF correction = 0.000120 Total force = 0.018857 Total SCF correction = 0.000155 Total force = 0.020215 Total SCF correction = 0.000193 Total force = 0.058765 Total SCF correction = 0.000241 Total force = 0.016998 Total SCF correction = 0.000205 Total force = 0.042967 Total SCF correction = 0.000238 Total force = 0.106226 Total SCF correction = 0.73 Total force = 0.137142 Total SCF correction = 0.71 Total force = 0.109549 Total SCF correction = 0.000108 Total force = 0.068723 Total SCF correction = 0.000103 Total force = 0.076599 Total SCF correction = 0.000168 Total force = 0.033233 Total SCF correction = 0.000342 Total force = 0.026883 Total SCF correction = 0.000248 Total force = 0.025846 Total SCF correction = 0.000378 Total force = 0.025596 Total SCF correction = 0.000225 Total force = 0.025482 Total SCF correction = 0.000275 Total force = 0.025508 Total SCF correction = 0.000128 I am thankful for any suggestions. Stephan Rix Institute for Inorganic und Analytical Chemistry Johannes Gutenberg-University Mainz, Germany -- next part -- An HTML attachment was scrubbed... URL: http://www.democritos.it/pipermail/pw_forum/attachments/20100915/b78f2dd0/attachment.htm
[Pw_forum] Re [8] : US-PP of Au
reza shidpoor wrote: > the calculations never finished because of segmentation fault. upgrade your compiler to something that works P. -- Paolo Giannozzi, Democritos and University of Udine, Italy
[Pw_forum] vc-relax problem when calculate lattice parameters
0.6244043290.6328600750.642528376 Al 0.70.30.25000 Al 0.30.70.75000 Ca 0.00.00.0 Ca 0.00.00.5 K_POINTS automatic 16 16 16 0 0 0 - Do you have some advises for the solution the case or elimination the Raman negative frequencies, any help is greatly appreciated. Thanks in advance Wang Di -- next part -- An HTML attachment was scrubbed... URL: http://www.democritos.it/pipermail/pw_forum/attachments/20100915/6e1d0aa5/attachment-0001.htm
[Pw_forum] problems with converge of geometric optimization
Hi Stephan, If the only problem is bfgs, you can change ion_dynamics to damp. Regards -- Jia Chen Dept of Chemistry Princeton University Princeton, NJ 08544
[Pw_forum] vc-relax problem when calculate lattice parameters
ynamics = 'bfgs' , > / > ATOMIC_SPECIES >Li6.94100 03-Li.LDA.fhi.UPF >Al 26.98154 13-Al.LDA.fhi.UPF >Ca 40.07800 20-Ca.LDA.fhi.UPF > F 18.99840 09-F.LDA.fhi.UPF > ATOMIC_POSITIONS crystal >Li 0.30.70.25000 >Li 0.70.30.75000 > F 0.3755956710.0084557460.142528376 > F 0.9915442540.3671399250.142528376 > F 0.6328600750.6244043290.142528376 > F 0.9915442540.6244043290.357471624 > F 0.6328600750.0084557460.357471624 > F 0.3755956710.3671399250.357471624 > F 0.6244043290.9915442540.857471624 > F 0.0084557460.6328600750.857471624 > F 0.3671399250.3755956710.857471624 > F 0.0084557460.3755956710.642528376 > F 0.3671399250.9915442540.642528376 > F 0.6244043290.6328600750.642528376 >Al 0.70.30.25000 >Al 0.30.70.75000 >Ca 0.00.00.0 >Ca 0.00.00.5 > K_POINTS automatic > 16 16 16 0 0 0 > > - > > Do you have some advises for the solution the case or elimination the Raman > negative frequencies, any help is greatly appreciated. > > Thanks in advance > Wang Di > > ___ > Pw_forum mailing list > Pw_forum at pwscf.org > http://www.democritos.it/mailman/listinfo/pw_forum > > -- Regards, MOHNISH, - Mohnish Pandey Y6927262,5th Year dual degree student, Department of Chemical Engineering, IIT KANPUR, UP, INDIA +919235721300 - -- next part -- An HTML attachment was scrubbed... URL: http://www.democritos.it/pipermail/pw_forum/attachments/20100915/02958e6c/attachment.htm
[Pw_forum] input dist.x
On Sep 15, 2010, at 4:28 , ?lvaro Alves wrote: > Dear QE users! Can someone give me an input of the tool dist.x ? it is described in the header of pwtools/dist.f P. --- Paolo Giannozzi, Dept of Physics, University of Udine via delle Scienze 208, 33100 Udine, Italy Phone +39-0432-558216, fax +39-0432-558222
[Pw_forum] Res: input dist.x
Thanks, Giannozzi. A. S. Santos Univesidade Federal Fluminense Niter?i-Rio de Janeiro-Brasil De: Paolo Giannozzi Para: PWSCF Forum Enviadas: Quarta-feira, 15 de Setembro de 2010 2:59:24 Assunto: Re: [Pw_forum] input dist.x On Sep 15, 2010, at 4:28 , ?lvaro Alves wrote: > Dear QE users! Can someone give me an input of the tool dist.x ? it is described in the header of pwtools/dist.f P. --- Paolo Giannozzi, Dept of Physics, University of Udine via delle Scienze 208, 33100 Udine, Italy Phone +39-0432-558216, fax +39-0432-558222 ___ Pw_forum mailing list Pw_forum at pwscf.org http://www.democritos.it/mailman/listinfo/pw_forum -- next part -- An HTML attachment was scrubbed... URL: http://www.democritos.it/pipermail/pw_forum/attachments/20100914/46b2f29c/attachment.htm
