exercises:2016_uzh_cmest:calculating_pdos
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Projected density of states for graphene and h-BN
In the following exercise we are going to look at the density of states of two similar 2D structures:
- Graphene
- hexagonal Boron Nitride
Both feature the same 2D crystal structure with the only difference being the lattice constant and that one consists of only carbons and the other of boron and nitride.
Similar to the previous exercise we write the coordinates in term of the unit cell:
- graphene_pdos.inp
&GLOBAL PROJECT graphene_pdos RUN_TYPE ENERGY PRINT_LEVEL MEDIUM &END GLOBAL &FORCE_EVAL METHOD Quickstep &DFT BASIS_SET_FILE_NAME BASIS_MOLOPT POTENTIAL_FILE_NAME POTENTIAL &POISSON PERIODIC XYZ &END POISSON &SCF SCF_GUESS ATOMIC EPS_SCF 1.0E-6 MAX_SCF 300 # The following settings help with convergence: ADDED_MOS 100 CHOLESKY INVERSE &SMEAR ON METHOD FERMI_DIRAC ELECTRONIC_TEMPERATURE [K] 300 &END SMEAR &DIAGONALIZATION ALGORITHM STANDARD EPS_ADAPT 0.01 &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 &PRINT &PDOS # print all projected DOS available: NLUMO -1 COMPONENTS &END &END &END DFT &SUBSYS &CELL # create a hexagonal unit cell: ABC 2.4612 2.4612 15.0 ALPHA_BETA_GAMMA 90. 90. 60. SYMMETRY HEXAGONAL PERIODIC XYZ # and replicate this cell (see text): MULTIPLE_UNIT_CELL 2 2 1 &END CELL &TOPOLOGY # also replicate the topology (see text): MULTIPLE_UNIT_CELL 2 2 1 &END TOPOLOGY &COORD SCALED C 1./3. 1./3. 0. C 2./3. 2./3. 0. &END &KIND C ELEMENT C BASIS_SET TZVP-MOLOPT-GTH POTENTIAL GTH-PBE &END KIND &END SUBSYS &END FORCE_EVAL
The replication of the unit cell before doing the calculation is necessary since we are currently sampling only at he $\Gamma$ point and we will otherwise do not have enough sampling points for the density of states. Another option (which we will look into in the next exercise) is to sample over k-points instead.
exercises/2016_uzh_cmest/calculating_pdos.1477853737.txt.gz · Last modified: 2020/08/21 10:15 (external edit)