[QE-users] Why does the difference between VASP and QE, even though they are BOMD theory
Pietro Delugas
pdelugas at sissa.it
Wed Apr 11 08:55:27 CEST 2018
Dear Venkataramana
Try to decrease conv_thr below 1.0e-9
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).
regards - pietro
On 11/04/2018 07:49, Venkataramana Imandi wrote:
> Dear QE users,
>
> Simulation cell parameters are same in the VASP and QE. In both cases,
> simulation started from the same input structure.
> I am using 6.2.1 version of QE.
> 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).
>
> VASP: I used RMM-DIIS for geometry optimization, Davidson
> diagaonalization or cg for electronic scf and Pt(PW91-ultrasoft),
> O(PW91-ultrasoft).
>
> For information,
> 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.
>
> But in QE, I obtained all O_ad sites except bridge site on Pt-surface.
> In QE, I found interlayer spacing(3rd and 2nd layer difference) varied
> >+0.05 angstroms more compared to initital structure.
>
> Thus, I found more relaxed structure in QE compared to VASP.
>
> Any suggestions are greatly appreciated.
>
> My input file as follow.
>
> &control
> calculation='relax'
> restart_mode='from_scratch',
> pseudo_dir = '/home2/oth/ch18ipf01/pseudopotential2/',
> prefix='pto'
> tprnfor = .true.,
> nstep = 200
> /
> &system
> ibrav=0,
> nat=49,
> ntyp=2,
> ! nspin = 2,
> ! starting_magnetization(1)=0.7,
> ecutwfc = 32.0,
> ecutrho = 320.0,
> occupations='smearing',
> smearing='methfessel-paxton',
> degauss=0.02
> /
> &electrons
> diagonalization='cg'
> conv_thr = 1.0e-6
> mixing_beta = 0.3
> electron_maxstep = 1000
> /
> &ions
> ion_dynamics='bfgs',
> /
> ATOMIC_SPECIES
> Pt 195.084 Pt.pbe-nd-rrkjus.UPF
> O 15.999 O.pbe-rrkjus.UPF
>
> ATOMIC_POSITIONS {angstrom}
> O 4.83670 3.24076 9.895064 1 1 1
> Pt 7.7079 5.67952 7.91015 1 1 1
> Pt 6.36297 8.19933 7.98784 1 1 1
> Pt 4.91919 6.00109 8.19464 1 1 1
> Pt 3.48056 8.20502 7.98339 1 1 1
> Pt 2.13171 5.68297 7.90776 1 1 1
> Pt 0.69985 8.11366 7.9477 1 1 1
> Pt 7.78611 0.73129 7.94675 1 1 1
> Pt 6.42371 3.08952 8.08857 1 1 1
> Pt 4.92315 0.76409 7.92858 1 1 1
> Pt 3.41889 3.09455 8.08213 1 1 1
> Pt 2.05589 0.73846 7.94323 1 1 1
> Pt 0.69979 3.32663 7.96547 1 1 1
> Pt 6.29321 4.95311 5.73597 1 1 1
> Pt 7.73513 7.49799 5.63702 1 1 1
> Pt 3.54425 4.96152 5.72897 1 1 1
> Pt 4.92162 7.32106 5.7753 1 1 1
> Pt 0.69791 5.10582 5.63088 1 1 1
> Pt 2.10707 7.50605 5.63432 1 1 1
> Pt 6.32478 0.10848 5.63611 1 1 1
> Pt 7.70985 2.61906 5.72581 1 1 1
> Pt 3.51897 0.11648 5.63414 1 1 1
> Pt 4.92144 2.53817 5.67277 1 1 1
> Pt 0.69984 0.23217 5.59048 1 1 1
> Pt 2.13138 2.62752 5.72184 1 1 1
> Pt 6.32344 6.78474 3.44718 1 1 1
> Pt 7.7339 9.3212 3.38713 1 1 1
> Pt 3.51851 6.7929 3.44491 1 1 1
> Pt 4.9219 9.19308 3.42498 1 1 1
> Pt 0.6991 6.90045 3.3778 1 1 1
> Pt 2.10972 9.32712 3.38533 1 1 1
> Pt 6.33835 1.94543 3.42008 1 1 1
> Pt 7.72421 4.42937 3.42142 1 1 1
> Pt 3.50426 1.95276 3.41781 1 1 1
> Pt 4.92063 4.34401 3.43929 1 1 1
> Pt 0.6992 2.09004 3.40181 1 1 1
> Pt 2.11503 4.43554 3.41785 1 1 1
> Pt 7.73571 6.2569 1.1 0 0 0
> Pt 6.32857 8.69414 1.1 0 0 0
> Pt 4.92143 6.2569 1.1 0 0 0
> Pt 3.51428 8.69414 1.1 0 0 0
> Pt 2.10714 6.2569 1.1 0 0 0
> Pt 0.7 8.69414 1.1 0 0 0
> Pt 7.73571 1.38241 1.1 0 0 0
> Pt 6.32857 3.81966 1.1 0 0 0
> Pt 4.92143 1.38241 1.1 0 0 0
> Pt 3.51428 3.81966 1.1 0 0 0
> Pt 2.10714 1.38241 1.1 0 0 0
> Pt 0.7 3.81966 1.1 0 0 0
>
> K_POINTS {automatic}
> 2 2 1 0 0 0
> CELL_PARAMETERS {angstrom}
> 8.4428549700000008 0.0000000000000000 0.0000000000000000
> 0.0000000000000000 9.7489691799999996 0.0000000000000000
> 0.0000000000000000 0.0000000000000000 19.1916000000000011
>
>
> With best regards
> Venkataramana Imandi
> Postdoctoral fellow
> IIT Madras, India.
>
>
>
>
>
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