Ionic contributions to the frequency dependent dielectric function of NaCl
Task
Calculation of the ionic contruibutions to the frequency dependent dielectric function of NaCl. Please have a look at the example on calculation of the static and frequency dependent dielectric properties of SiC first. The same procedures dor the electronic contributions apply to this example.
Input
POSCAR
NaCl FCC 5.55596202 0.5000000000000000 0.5000000000000000 0.0000000000000000 0.0000000000000000 0.5000000000000000 0.5000000000000000 0.5000000000000000 0.0000000000000000 0.5000000000000000 Na Cl 1 1 Direct 0.0000000000000000 0.0000000000000000 0.0000000000000000 0.5000000000000000 0.5000000000000000 0.5000000000000000
KPOINTS
Gamma-centred 11x11x11 Monkhorst-Pack grid 0 G 11 11 11 0 0 0
INCAR
- INCAR file for the static calculation:
PREC = High ISMEAR = 0 ; ISIGMA = 0.01 EDIFF = 1.E-8 GGA = PS
- INCAR electronic contributions to the frequency dependent dielectric function[1](see other tutorials for more advanced options):
PREC = High ISMEAR = 0 ; ISIGMA = 0.01 EDIFF = 1.E-8 GGA = PS ALGO = Exact LOPTICS = .TRUE.
PREC = High ISMEAR = 0 ; ISIGMA = 0.01 EDIFF = 1.E-8 GGA = PS EDIFF = 1.E-8 #The ionic dielectric function can be calculated in two ways:################ #1# DFPT (faster), but does not allow for METAGGA use. ###################### IBRION = 8; LEPSILON=.TRUE. #2# Finite differences (slower). ############################################ #IBRION = 6; LPEAD=.TRUE; LCALCEPS=.TRUE. #NFREE = 2 ; POTIM = 0.015 #In both 1 and 2 the calculated dielectric function is in vasprun.xml #######
Calculation
Download all necessary files and run doall.sh. An Awk script ("extract_diel_vasprun") is used to extract the dielectric function from the vasprun.xml file and write it into a easy to plot two-column format. If everything goes well you will obtain two files ("diel.electron.dat" and "diel.ion.dat"). The two dielectric functions have been plotted in the following figure.
Download
NaCl_dielectric.tgz NaCl_dielectric.tgz
References
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