Graphite MBD binding energy: Difference between revisions

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== Calculation ==
== Running this example ==
 
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 example
{{TAG|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 {{TAG|Many-body dispersion energy}}).


Once again, the calculation is performed in two steps  
Once again, the calculation is performed in two steps  
Line 93: Line 77:
the RPA reference of 0.048 eV/atom
the RPA reference of 0.048 eV/atom
<ref name="lebegue"/>.
<ref name="lebegue"/>.


== Download ==
== Download ==

Revision as of 21:07, 24 June 2019

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


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

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