VASP Computing Generalized Stacking Fault Energy of Au

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VASP: Genearlized Stacking Fault Energy of Au


Input files

Here are the basic input files required for VASP calculation. Some of the files need to be changed since we need to perform a large number of calculations.

INCAR

System = fcc Au
LWAVE = .FALSE.
ENCUT  =  400
ISMEAR  = 1
SIGMA = 0.1
ISIF = 2

KPOINTS

test convergence
0        0 = automatic generation of k-points
Monkhorst
7 7 11
0 0 0

POSCAR

POSCAR for FCC Au (created manually)
4.0605
 1.22474487139159 0                0
 0                1.73205080756888 0
 0                0                0.70710678118655
6
Cartesian  (real coordinates r)
 0                0                0
 0.40824829046386 0.57735026918963 0
 0.81649658092773 1.15470053837925 0
 0.61237243569579 0                0.35355339059327
 1.02062072615966 0.57735026918963 0.35355339059327
 0.20412414523193 1.15470053837925 0.35355339059327

You also need to put the LDA pseudopotential file as POTCAR in this directory.

Results

Perfect crystal

The following table shows energy convergence with k-points. (Reference value from Au_bulk calculation: E = -4.39 eV/atom.)

KPOINTS E (eV/atom) optimal number of CPUs computational time (second)
3x3x3 -4.4735468 -- --
5x5x5 -4.4121563 -- --
7x7x7 -4.4043722 -- --
7x7x11 -4.3981093 16 341
7x5x13 -4.3974777 16 291

Unrelaxed stacking fault energy

We now fix KPOINTS at 7x5x13, for which the energy of perfect crystal is E=-4.3974777 (eV/atom).

To create a stacking fault, we shift the repeat vector b in the x-direction by sqrt(6)/6. The new POSCAR file is (notice the change in 3rd line). 

POSCAR for FCC Au (created by tcl)
4.0605
 1.22474487139159 0                0
 0.40824829046386 1.73205080756888 0
 0                0                0.70710678118655
6
Cartesian  (real coordinates r)
 0                0                0
 0.40824829046386 0.57735026918963 0
 0.81649658092773 1.15470053837925 0
 0.61237243569579 0                0.35355339059327
 1.02062072615966 0.57735026918963 0.35355339059327
 0.20412414523193 1.15470053837925 0.35355339059327
Unrelaxed stacking fault energy
E1 (raw data) ?? (eV)
E0 (perfect crystal) -4.3974777 (eV/atom)
Ex (excess) = (E1-E0*6) ?? (eV)
Area ?? (angstrom^2)
Esf (unrelaxed) = Ex / Area ?? (eV/angstrom^2) =  ?? (mJ/m^2)

Relaxed stacking fault energy

We now fix KPOINTS at 7x7x11, for which the energy of perfect crystal is E = ???? (eV/atom).

Unrelaxed stacking fault energy
E1 (raw data) ?? (eV)
E0 (perfect crystal) ?? (eV/atom)
Ex (excess) = (E1-E0*6) ?? (eV)
Area ?? (angstrom^2)
Esf (unrelaxed) = Ex / Area ?? (eV/angstrom^2) =  ?? (mJ/m^2)


Unrelaxed generalized stacking fault energy

We now fix KPOINTS at 7x7x11, for which the energy of perfect crystal is E = ???? (eV/atom).

Unrelaxed stacking fault energy
E1 (raw data) ?? (eV)
E0 (perfect crystal) ?? (eV/atom)
Ex (excess) = (E1-E0*6) ?? (eV)
Area ?? (angstrom^2)
Esf (unrelaxed) = Ex / Area ?? (eV/angstrom^2) =  ?? (mJ/m^2)


Relaxed generalized stacking fault energy

We now fix KPOINTS at 7x7x11, for which the energy of perfect crystal is E = ???? (eV/atom).

Unrelaxed stacking fault energy
E1 (raw data) ?? (eV)
E0 (perfect crystal) ?? (eV/atom)
Ex (excess) = (E1-E0*6) ?? (eV)
Area ?? (angstrom^2)
Esf (unrelaxed) = Ex / Area ?? (eV/angstrom^2) =  ?? (mJ/m^2)
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