Fcc Si DOS: Difference between revisions

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Description: plot the DOS in fcc Si
{{Template:Bulk_systems - Tutorial}}
----
*INCAR
System = fcc Si
# ICHARG=11 #charge read file
ENCUT  =    240
ISMEAR = -5 #tetrahedron
LORBIT=11


*KPOINTS
== Task ==
k-points
 
  0
Calculation of the DOS in fcc Si.
Monkhorst Pack
 
  21 21 21
== Input ==
  0  0  0


*POSCAR
=== {{FILE|POSCAR}} ===
  fcc Si:
  fcc Si:
   3.9
   3.9
Line 25: Line 17:
  0 0 0
  0 0 0


*The bash-script <tt>plotdos</tt> invokes ''awk'' and ''gnuplot'' to get the DOS from the {{FILE|vasprun.xml}} file and plot it.
=== {{FILE|INCAR}} ===
{{TAGBL|System}} = fcc Si
# {{TAGBL|ICHARG}} = 11 #charge read file
{{TAGBL|ENCUT}}  =    240
{{TAGBL|ISMEAR}} = -5 #tetrahedron
{{TAGBL|LORBIT}} = 11
 
=== {{FILE|KPOINTS}} ===
k-points
  0
Monkhorst Pack
  21 21 21
  0  0  0
 
== Calculation ==
 
*Perform a static ({{TAG|NSW}}=0, {{TAG|IBRION}}=-1) self consistent calculation for the DOS (the DOS is found in the {{TAG|DOSCAR}} file.
 
*For large systems:
**Converge with a small number of k points.
**Increase the number of k points for the DOS and set {{TAG|ICHARG}}=11 (charge density from the last self-consistent run). {{TAG|ICHARG}}=11 treats each k point independently and keeps the charge density and the potential fixed.
 
*Read {{TAG|CHGCAR}} from previous run. To copy the self-consistent charge density of example {{TAG|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 {{TAG|CHGCAR}} and will terminate.
 
*The smearing of the k points is set to the tetrahedron method with Blöchl corrections ({{TAG|ISMEAR}}=-5 to fi the problem
[[File:Fig Si 2.png|300px]]
 
*To plot the DOS use p4vasp:
[[File:Fig Si 3.png|600px]]
 
 
*Alternatively the bash-script <tt>plotdos.sh</tt> invokes ''awk'' and ''gnuplot'' to get the DOS from the {{FILE|vasprun.xml}} file and plot it.
<pre>
<pre>
awk 'BEGIN{i=1} /dos>/,\
awk 'BEGIN{i=1} /dos>/,\
Line 44: Line 68:
rm dos.dat plotfile
rm dos.dat plotfile
</pre>
</pre>
[[File:Fig Si 4.png|600px]]


== Download ==
== Download ==
[http://www.vasp.at/vasp-workshop/examples/fccSidos.tgz fccSidos.tgz]
[[Media:FccSidos.tgz| fccSidos.tgz]]
 
----
{{Template:Bulk_systems}}
[[VASP_example_calculations|To the list of examples]] or to the [[The_VASP_Manual|main page]]


[[Category:Examples]]
[[Category:Examples]]

Latest revision as of 13:24, 14 November 2019

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

  • To plot the DOS use p4vasp:


  • 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

Download

fccSidos.tgz