All requests for technical support from the VASP group must be addressed to: vasp.materialphysik@univie.ac.at

Fcc Si DOS

From Vaspwiki
Jump to: navigation, search

Task

Calculation of the DOS in fcc Si.

Input

POSCAR

fcc Si:
 3.9
 0.5 0.5 0.0
 0.0 0.5 0.5
 0.5 0.0 0.5
   1
cartesian
0 0 0

INCAR

System = fcc Si 
# ICHARG = 11 #charge read file
ENCUT  =    240
ISMEAR = -5 #tetrahedron
LORBIT = 11

KPOINTS

k-points
 0
Monkhorst Pack
 21 21 21
 0  0  0

Calculation

  • Perform a static (NSW=0, IBRION=-1) self consistent calculation for the DOS (the DOS is found in the DOSCAR file.
  • For large systems:
    • Converge with a small number of k points.
    • Increase the number of k points for the DOS and set ICHARG=11 (charge density from the last self-consistent run). ICHARG=11 treats each k point independently and keeps the charge density and the potential fixed.
  • Read CHGCAR from previous run. To copy the self-consistent charge density of example fcc_Si to your current working

directory (assumed to be fccSidos), type: $ cp ../fccSi/CHGCAR . You must do this otherwise VASP can not read the CHGCAR and will terminate.

  • The smearing of the k points is set to the tetrahedron method with Blöchl corrections (ISMEAR=-5 to fi the problem

Fig Si 2.png

  • To plot the DOS use p4vasp:

Fig Si 3.png


  • Alternatively the bash-script plotdos.sh invokes awk and gnuplot to get the DOS from the vasprun.xml file and plot it.
awk 'BEGIN{i=1} /dos>/,\
                /\/dos>/ \
                 {a[i]=$2 ; b[i]=$3 ; i=i+1} \
     END{for (j=12;j<i-5;j++) print a[j],b[j]}' vasprun.xml > dos.dat

ef=`awk '/efermi/ {print $3}' vasprun.xml`

cat >plotfile<<!
# set term postscript enhanced eps colour lw 2 "Helvetica" 20
# set output "optics.eps"
plot "dos.dat" using (\$1-$ef):(\$2) w lp
! 

gnuplot -persist plotfile

rm dos.dat plotfile

Fig Si 4.png

Download

fccSidos.tgz

Back to the main page.