Graphite MBD binding energy

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Task

Determine the interlayer binding energy of graphite in its experimental structure using the MBD@rsSCS method of Tchatchenko et al. to account for van der Waals interactions.

Input

POSCAR

• Graphite:

graphite
1.0
1.22800000 -2.12695839  0.00000000
1.22800000  2.12695839  0.00000000
0.00000000  0.00000000  6.71
4
direct
   0.00000000  0.00000000  0.25000000
   0.00000000  0.00000000  0.75000000
   0.33333333  0.66666667  0.25000000
   0.66666667  0.33333333  0.75000000

• Graphene:

graphite
1.0
1.22800000 -2.12695839  0.00000000
1.22800000  2.12695839  0.00000000
0.00000000  0.00000000  20.
2
direct
   0.00000000  0.00000000  0.25000000
   0.33333333  0.66666667  0.25000000

INCAR

IVDW = 202           
LVDWEXPANSION =.TRUE. 
NSW = 1 
IBRION = 2
ISIF = 4
PREC = Accurate
EDIFFG = 1e-5
LWAVE = .FALSE.
LCHARG = .FALSE.
ISMEAR = -5
SIGMA = 0.01
EDIFF = 1e-6
ALGO = Fast
NPAR = 2

KPOINTS

• Graphite:

Monkhorst Pack
0
gamma
16 16 8
0 0 0

• Graphene:

Monkhorst Pack
0
gamma
16 16 1
0 0 0

Calculation

Semilocal DFT at the GGA level underestimates long-range dispersion interactions. In the case of graphite, PBE predicts the interlayer binding energy of ~1 meV/atom which is too small compared to the RPA reference of 0.048 eV/atom . In contrast, the pairwise correction scheme of Tkatchenko and Scheffler, overestimates this quantity strongly (0.083 eV/atom, see example Graphite TS binding energy). In this example we show that this problem can be eliminated by if many-body effects in dispersion energy are taken into account using the MBD@rsSCS method of Tchatchenko et al. (see Many-body dispersion energy).

Once again, the calculation is performed in two steps (single-point calculations) in which the energy for bulk graphite and for graphene are obtained. The binding energy is computed automatically and it is written in the file results.dat.

The computed value of 0.050 eV/A is now fairly close to the RPA reference of 0.048 eV/atom .

Download

graphiteBinding_mdb.tgz

References

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