Dielectric properties of Si
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Task
Calculation of the static and frequency dependent dielectric properties of Si. Please have a look at the example on calculation of the static and frequency dependent dielectric properties of SiC first. The same procedures apply to this example.
Input
POSCAR
system Si 5.430 0.5 0.5 0.0 0.0 0.5 0.5 0.5 0.0 0.5 2 cart 0.00 0.00 0.00 0.25 0.25 0.25
INCAR
- INCAR file for the static calculation:
## Static dielectric properties by means of DFPT #NBANDS = 4 #EDIFF = 1E-6 #LEPSILON = .TRUE. ## try to add this to the DFPT calculation #LPEAD = .TRUE. ## to get the ionic contributions to the ## static dielectric properties from ## perturbation theory #IBRION = 8 ## Static dielectric properties by means of PEAD #EDIFF = 1E-8 # finite field requires very tight convergence #LCALCEPS = .TRUE. #NELM = 100 ## Leave this in ISMEAR = 0 SIGMA = 0.01 GGA = PE
- INCAR for the frequency dependent calculation:
## Frequency dependent dielectric tensor without ## local field effects #ALGO = Exact #NBANDS = 64 #LOPTICS = .TRUE. ; CSHIFT = 0.1 #NEDOS = 2000 ## and you might try with the following #LPEAD = .TRUE. ## Frequency dependent dielectric tensor with and ## without local field effects in RPA and due to ## changes in the DFT xc-potential ## N.B.: beware one first has to have done a ## calculation with LOPTICS = .TRUE. (see above) #ALGO = CHI ; LSPECTRAL = .FALSE. #LRPA = .FALSE. ## be sure to take the same number of bands as for ## the LOPTICS = .TRUE. calculation, otherwise the ## WAVEDER file is not read correctly # NBANDS = 64 ## Leave this in ISMEAR = 0 SIGMA = 0.01 GGA = PE