Example: Phonons¶
A phonon calculation should be performed at the equilibrium geometry.
In the first calculation we optimize the geometry, including the lattice vectors. We also set the criteria a bit more strict.
$ADFBIN/band << eor
Title Graphene geometry optimization
Units
Length Angstrom
end
! For Graphene we need to use a symmetryc grid
KSpace 5 &
Grid Symmetric
End
ATOMS
C 0.0 0.0 0.0
C 1.23 0.7101408312 0.0
END
Lattice
2.46 0.000000 0
1.23 2.130422493 0
End
GeoOpt
OptimizeLattice true
Converge grad=1e-5
End
BasisDefaults
BasisType DZ
end
end input
eor
mv RUNKF Graphene.runkf
In the second calculation we use the pre-optimized geometry. (See details of the Restart key block) Then we define a supercell and perform a phonon run by using the RunType and PhononConfig key blocks. Note that KSpace
can be chosen a bit lower, since we now have a bigger unit cell.
$ADFBIN/band << eor
Title Graphene phonon calc
Units
Length Angstrom
end
KSpace 3 &
Grid Symmetric
End
Restart
File Graphene.runkf
Geometry
End
runtype
phonons
end
phononConfig
stepSize 0.0913
superCell
2 0
0 2
subend
end
ATOMS
C 0.0 0.0 0.0
C 1.23 0.7101408312 0.0
END
Lattice
2.46 0.000000 0
1.23 2.130422493 0
End
BasisDefaults
BasisType DZ
end
end input
eor