Graphite MBD binding energy: Difference between revisions

Revision as of 21:10, 24 June 2019

Overview > fcc Si > fcc Si DOS > fcc Si bandstructure > cd Si > cd Si volume relaxation > cd Si relaxation > beta-tin Si > fcc Ni > graphite TS binding energy > graphite MBD binding energy > graphite interlayer distance > List of tutorials

Task

In this example you will 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.

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 ^[1]. In contrast, the pairwise correction scheme of Tkatchenko and Scheffler, overestimates this quantity strongly (0.083 eV/atom, see the Graphite TS binding energy example). Here 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).

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

Running this example

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 ^[1].

Download

graphiteBinding_mdb.tgz

References

↑ ^a ^b S. Lebègue, J. Harl, Tim Gould, J. G. Ángyán, G. Kresse, and J. F. Dobson, Phys. Rev. Lett. 105, 196401 (2010).

Overview > fcc Si > fcc Si DOS > fcc Si bandstructure > cd Si > cd Si volume relaxation > cd Si relaxation > beta-tin Si > fcc Ni > graphite TS binding energy > graphite MBD binding energy > graphite interlayer distance > List of tutorials

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[lebegue-1] S. Lebègue, J. Harl, Tim Gould, J. G. Ángyán, G. Kresse, and J. F. Dobson, Phys. Rev. Lett. 105, 196401 (2010).

[1]

@@ Line 3: / Line 3: @@
 == 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.
+In this example you will 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.
+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 <ref name="lebegue"/>.
+In contrast, the pairwise correction scheme of Tkatchenko and Scheffler, overestimates  this quantity strongly (0.083 eV/atom, see the [[Graphite TS binding energy]] example).
+Here 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]]).
 == Input ==