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# CO on Ni 111 surface

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Adsorbtion of a CO molecule at the top site of a Ni (111) surface.

## Input

### POSCAR

Ni - (111) + CO on-top
3.53
.70710678  .0000000  .000000
-0.35355339 0.6123724  .000000
.000000    .000000  5.1961524
5 1 1
selective dynamics
direct
.00000000   .00000000   .00000000  F  F  F
.33333333   .66666667   .11111111  F  F  F
.66666667   .33333333   .22222222  F  F  F
.00000000   .00000000   .33333333  T  T  T
.33333333   .66666667   .44444444  T  T  T
.33333333   .66666667   .54029062  T  T  T
.33333333   .66666667   .60298866  T  T  T

• CO molecule put above surface atom "on-top".
• ${\displaystyle z_{{{\mathrm {C}}}}=(.540-.444)\cdot 5.196\cdot 3.53\approx 1.76}$ ${\displaystyle \AA }$.
• ${\displaystyle d_{{{\mathrm {CO}}}}=(.603-.540)\cdot 5.196\cdot 3.53\approx 1.16}$ ${\displaystyle \AA }$.

### INCAR

  ISTART = 0
ICHARG = 2

general:
SYSTEM = CO adsorption on Ni(111)
ENMAX  = 400
ISMEAR =    2  ; SIGMA = 0.2
ALGO= Fast
EDIFF = 1E-6

dynamic:
NSW=100
POTIM = 0.2
IBRION = 1


### KPOINTS

K-Points
0
Monkhorst-Pack
9 9 1
0 0 0


## Calculation

• Two additional atom types (C and O) in the calculations: append C and O potentials to the POTCAR file.
• The sample output for the forces should look like the following:
POSITION                                       TOTAL-FORCE (eV/Angst)
-----------------------------------------------------------------------------------
0.00000      0.00000      0.00000         0.000000      0.000000      0.175780
0.00000      1.44112      2.03805         0.000000      0.000000     -0.104008
1.24804      0.72056      4.07609         0.000000      0.000000     -0.036305
0.00000      0.00000      6.10852         0.000000      0.000000     -0.083336
0.00000      1.44112      8.15366         0.000000      0.000000      0.009539
0.00000      1.44112      9.90873         0.000000      0.000000      0.011228
0.00000      1.44112     11.06339         0.000000      0.000000      0.027102
-----------------------------------------------------------------------------------
total drift:                               -0.000093     -0.000213      0.019852

• Small outward relaxation of surface due to adsorption: ${\displaystyle \Delta d_{{12}}=(8.154-6.109)/2.038=0.4\%}$.
• CO geometry change: ${\displaystyle d_{{{\mathrm {CO}}}}=11.063-9.909=1.155}$ ${\displaystyle \AA }$; ${\displaystyle z_{{{\mathrm {C}}}}=9.909-8.154=1.755}$ ${\displaystyle \AA }$.
• Visualize the structure using p4vasp: