[QE-users] O_ad(O-adsorption) is not binding at bridge position on Pt-surface

[Venkataramana Imandi]

Dear Ari,

Sorry, I didn't mention that I also tried by fixing coordinate of O_ad at a
bridge position.
It resulted the Pt atoms moving, in such way that O_ad becomes three-fold
site(either fcc or hcp).

With best regards
Venkataramana Imandi
Postdoctoral fellow
IIT Madras, India.


On Tue, Apr 10, 2018 at 2:44 PM, Venkataramana Imandi <
venkataramana.imandi at gmail.com> wrote:

>
> Dear QE community,
>
> I am a new user of Quantum espresso simulation package. I installed 6.2.1
> Quantum espresso in the Linux-X86_64-INTEL-MPI. I want to find out the
> binding energy of O_ad at various sites(top,bridge,hcp and fcc) on
> Pt-surface and Pt-Ni alloy surface. In the beginning, i have tried on
> Pt-surface, and I got O_ad at top, hcp and fcc sites on Pt-surface,
> however, i couldn't find O_ad at bridge position.
> I have tried all possible ways of getting O_ad at the bridge
> position(between Pt-Pt). None of them were given succussful results, and
> the resulted O_ad comes to either fcc or hcp position. All possible ways:
> using with and without spin-polarization, davidson diagonalization anc cg,
> option (nosym = .TRUE. and .FALSE.), mixing mode(plain, local-TF and TF),
> changing mixing-beta(0.2, 0.3 and 0.5), neutral, negative charge(-2) and
> different simulation setup (present 24 atoms to 48 Pt atoms). The last
> option, i used different pseudopotential(Pt.pw91-n-van.UPF and
> O.pw91-van_ak.UPF), herein, i got error as follows (Error in
> scalartorealdp  Too few elements found). Now i stopped trials.
> I ask you can anyone do calculation in your simulation setup with the
> given input file, tell me the where the problem is.
>
> I really thanks to you in advance for any suggestions regarding this.
> For information, i used VASP in the last year, therein, i obtained O_ad at
> all sites on Pt-surface.
>
>  &control
>     calculation='relax'
>     restart_mode='from_scratch',
>     pseudo_dir = '/home2/oth/ch18ipf01/pseudopotential2/',
>     prefix='pt'
>     tprnfor = .true.,
>     nstep = 200
>  /
>  &system
>     ibrav=0,
>     nat=25,
>     ntyp=2,
>     ! nspin = 2,
>     ! starting_magnetization(1)=0.7,
>     ecutwfc = 32.0,
>     ecutrho = 320.0,
>     occupations='smearing',
>     smearing='methfessel-paxton',
>     degauss=0.02
>    ! tot_charge = -2,
>     nosym = .TRUE.
>  /
>  &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     3.45091550          1.17466050         13.69732100  1 1 1
> Pt    4.84778787          1.20016667         12.44963917  1 1 1
> Pt    3.46185858          3.60066659         12.44963917  1 1 1
> Pt    2.07592929          1.20016667         12.44963917  1 1 1
> Pt    0.69000000          3.60066659         12.44963917  1 1 1
> Pt    3.46185858          0.40000000         10.18642611  1 1 1
> Pt    4.84778787          2.80049996         10.18642611  1 1 1
> Pt    0.69000000          0.40000000         10.18642611  1 1 1
> Pt    2.07592929          2.80049996         10.18642611  1 1 1
> Pt    3.46185858          2.00033330          7.92321305  1 1 1
> Pt    4.84778787          4.40083326          7.92321305  1 1 1
> Pt    0.69000000          2.00033330          7.92321305  1 1 1
> Pt    2.07592929          4.40083326          7.92321305  1 1 1
> Pt    4.84778787          1.20016667          5.66000000  1 1 1
> Pt    3.46185858          3.60066659          5.66000000  1 1 1
> Pt    2.07592929          1.20016667          5.66000000  1 1 1
> Pt    0.69000000          3.60066659          5.66000000  1 1 1
> Pt    3.46185858          0.40000000          3.39678694  0 0 0
> Pt    4.84778787          2.80049996          3.39678694  0 0 0
> Pt    0.69000000          0.40000000          3.39678694  0 0 0
> Pt    2.07592929          2.80049996          3.39678694  0 0 0
> Pt    3.46185858          2.00033330          1.13357388  0 0 0
> Pt    4.84778787          4.40083326          1.13357388  0 0 0
> Pt    0.69000000          2.00033330          1.13357388  0 0 0
> Pt    2.07592929          4.40083326          1.13357388  0 0 0
>
> K_POINTS {automatic}
> 3 3 1 0 0 0
> CELL_PARAMETERS {angstrom}
> 5.5437171600     0.0000000000     0.0000000000
> 0.0000000000     4.8009999000     0.0000000000
> 0.0000000000     0.0000000000    25.5792783300
>
>
> With best regards
> Venkataramana Imandi
> Postdoctoral fellow
> IIT Madras, India.
>
>
>
>
>
>
>


-- 
venkataramana
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