# Ni 111 surface high precision

Calculation of the adsorption energies and the work function of a Ni (111) surface with high precision.

## Input

### POSCAR

 fcc (111) surface
3.53000000000000
0.7071067800000000    0.0000000000000000    0.0000000000000000
-0.3535533900000000    0.6123724000000000    0.0000000000000000
0.0000000000000000    0.0000000000000000    5.1961523999999999
Ni
5
Selective dynamics
Direct
0.0000000000000000  0.0000000000000000  0.0000000000000000   F   F   F
0.3333333300000021  0.6666666699999979  0.1111111100000031   F   F   F
0.6666666699999979  0.3333333300000021  0.2222222199999990   F   F   F
-0.0000000000000000 -0.0000000000000000  0.3320935940210170   T   T   T
0.3333333300000021  0.6666666699999979  0.4413539967541983   T   T   T

0.00000000E+00  0.00000000E+00  0.00000000E+00
0.00000000E+00  0.00000000E+00  0.00000000E+00
0.00000000E+00  0.00000000E+00  0.00000000E+00
0.00000000E+00  0.00000000E+00  0.00000000E+00
0.00000000E+00  0.00000000E+00  0.00000000E+00


### INCAR

 ENMAX = 400

general:
SYSTEM = clean nickel (111) surface
ISTART = 0
ICHARG = 2
ISMEAR = 2 ; SIGMA = 0.2
ALGO = Fast
EDIFF = 1E-6

special:
LVHAR = .TRUE.
#  LVTOT = .TRUE.

• Run a single point calculation for the Ni(111) clean surface at a higher cutoff (400eV), which is needed to compute the adsorption energy.
• Potentials for O and C require an energy cut-off of 400eV:
• Previous calculation for clean cannot be used as reference.
• Recalculate with same energy cut-off.

### KPOINTS

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


## Calculation

• Change of cut-off lowers total energy:
• -25.732 eV (270 eV); -25.737 eV (400 eV).
• Becomes more important for larger cells.
• The adsorption energy is calculated in the following way:
• ${\displaystyle E_{\mathrm {ads} }=E_{\mathrm {total} }-E_{\mathrm {clean} }-E_{\mathrm {CO} }}$.
• ${\displaystyle E_{\mathrm {ads} }=-40.829+25.737+14.835=-0.257}$ eV.

### Work function

• We use this run also to calculate the work-function of Ni(111).
• Use p4vasp to show the planar average of the potential:

• Vacuum potential ${\displaystyle E^{\mathrm {vac} }=5.45}$ eV.
• Fermi level ${\displaystyle \epsilon _{\mathrm {F} }=0.224}$ eV. (from OUTCAR file).
• Work function ${\displaystyle \Phi =E^{\mathrm {vac} }-\epsilon _{\mathrm {F} }=5.23}$ eV.