# The calculation of band structure of defective graphene

Tianshu Jiang in Beijing jts2t... at gmail.com
Thu Aug 23 10:44:10 CEST 2018

Hello community,

I have been calculating the band structure of different graphene type
(monolayer, bilayer, defective, etc). In defective situation, I set a 5×5
unit cell and remove one atom in center of the structure.
After relax, I get the coordinates of the rest 49 atoms.
&FORCE_EVAL
METHOD Quickstep
&DFT
BASIS_SET_FILE_NAME  ./BASIS_MOLOPT
POTENTIAL_FILE_NAME  GTH_POTENTIALS

&POISSON
PERIODIC XYZ
&END POISSON
&QS
EPS_DEFAULT 1.0E-10
EXTRAPOLATION USE_GUESS
&END QS
&SCF
SCF_GUESS ATOMIC
EPS_SCF 1.0E-6
MAX_SCF 300

# The following settings help with convergence:
# CHOLESKY INVERSE
&SMEAR ON
METHOD FERMI_DIRAC
ELECTRONIC_TEMPERATURE [K] 300
&END SMEAR
&DIAGONALIZATION
ALGORITHM STANDARD
&END DIAGONALIZATION
&MIXING
METHOD BROYDEN_MIXING
ALPHA 0.2
BETA 1.5
NBROYDEN 8
&END MIXING
&END SCF

&XC
&XC_FUNCTIONAL PBE
&END XC_FUNCTIONAL
&END XC
&KPOINTS
SCHEME MONKHORST-PACK 3 3 1
SYMMETRY OFF
WAVEFUNCTIONS REAL
FULL_GRID .TRUE.
PARALLEL_GROUP_SIZE 0
&BAND_STRUCTURE
FILE_NAME 49_atom_6.bs
&KPOINT_SET
UNITS CART_BOHR
#UNITS B_VECTOR
SPECIAL_POINT 0.0 0.0 0.0    #\gamma point
SPECIAL_POINT 1./2. 0.0 0.0  # M point
#SPECIAL_POINT 2./3. 1./3. 0.0 # K point
SPECIAL_POINT 1./3. 1./3. 0.0  # K point
SPECIAL_POINT 0.0 0.0 0.0
NPOINTS 80
&END
&END BAND_STRUCTURE
&END KPOINTS

&SUBSYS
&CELL
ABC 12.306 12.306 15.0
ALPHA_BETA_GAMMA 90. 90. 60.
SYMMETRY HEXAGONAL
PERIODIC XYZ
&END CELL
&TOPOLOGY
COORD_FILE_FORMAT xyz
COORD_FILE_NAME ./50atom_2.xyz
&END TOPOLOGY

&KIND C
ELEMENT C
BASIS_SET DZVP-MOLOPT-GTH
&END KIND
&END SUBSYS

Here is part of my settings, but &COOR part not included ( the versionof
cp2k is 4.1). After the convergence of SCF iteration,  I plot the band
structure, listed be
low, which are quite different from the benchmark in some papers. Can
anyone help me with the situation ? Where is the problem and how should I
correct them ?

Expect replies from you.

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