MgO optimum mixing: Difference between revisions

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Description: find optimum HSE mixing parameter for MgO
{{Template:Hybrid_functionals - Tutorial}}


----
== Task ==
*{{TAG|INCAR}}
<pre>
##############################################
## Optimum HSE mixing parameter (AEXX) for MgO
## Expt gap = 7.8 eV
## fit gap wrt. 0<AEXX<1
## Compute the bandgap using different value of AEXX
## in the range (0,1) and find the value which leads
## to the best agreement with the experimental gap.
## hint: the gap grows lineraly with AEXX
## Better preconverge with PBE first!
##############################################
 
## Selects the HSE06 hybrid function
#LHFCALC = .TRUE. ; HFSCREEN = 0.2 ; AEXX=0.25 
#ALGO = D ; TIME = 0.4
 
## Leave this in
ISMEAR =  0
SIGMA  =  0.01
GGA    = PE


</pre>
Find optimum HSE mixing parameter for MgO.


*{{TAG|KPOINTS}}
== Input ==
<pre>
k-points
0
Gamma
  4  4  4
  0  0  0
</pre>


*{{TAG|POSCAR}}
=== {{TAG|POSCAR}} ===
<pre>
<pre>
MgO
MgO
Line 47: Line 19:
0.50 0.0 0.0
0.50 0.0 0.0
</pre>
</pre>
=== {{TAG|INCAR}} ===
##############################################
## Optimum HSE mixing parameter ({{TAGBL|AEXX}}) for MgO
## Expt gap = 7.8 eV
## fit gap wrt. 0<{{TAGBL|AEXX}}<1
## Compute the bandgap using different value of {{TAGBL|AEXX}}
## in the range (0,1) and find the value which leads
## to the best agreement with the experimental gap.
## hint: the gap grows lineraly with {{TAGBL|AEXX}}
## Better preconverge with PBE first!
##############################################
   
## Selects the HSE06 hybrid functional
#{{TAGBL|LHFCALC}} = .TRUE. ; {{TAGBL|HFSCREEN}} = 0.2 ; {{TAGBL|AEXX}}=0.25 
#{{TAGBL|ALGO}} = D ; {{TAGBL|TIME}} = 0.4
     
## Leave this in
{{TAGBL|ISMEAR}} =  0
{{TAGBL|SIGMA}}  =  0.01
{{TAGBL|GGA}}    = PE
=== {{TAG|KPOINTS}} ===
<pre>
k-points
0
Gamma
  4  4  4
  0  0  0
</pre>
== Calculation ==


*script to extract G-eigenvalues and calculate the bandgap
*script to extract G-eigenvalues and calculate the bandgap
Line 58: Line 62:
The bandgap is obainted by substracting the eigenvalues written in cband.dat (conduction band  
The bandgap is obainted by substracting the eigenvalues written in cband.dat (conduction band  
minimum at Gamma) and vband.dat (valence band maximum at Gamma)
minimum at Gamma) and vband.dat (valence band maximum at Gamma)
== Used INCAR Tags ==
{{TAG|AEXX}}, {{TAG|ALGO}}, {{TAG|GGA}}, {{TAG|HFSCREEN}}, {{TAG|ISMEAR}}, {{TAG|LHFCALC}}, {{TAG|SIGMA}}


== Download ==
== Download ==
[http://www.vasp.at/vasp-workshop/examples/5_2_MgO_mixing.tgz 5_2_MgO_mixing.tgz]
[[Media:5 2 MgO mixing.tgz| 5_2_MgO_mixing.tgz]]
----
[[VASP_example_calculations|To the list of examples]] or to the [[The_VASP_Manual|main page]]
{{Template:Hybrid_functionals}}


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

Latest revision as of 20:11, 14 March 2022

Task

Find optimum HSE mixing parameter for MgO.

Input

POSCAR

MgO
-18.79350000000000000000
0.5 0.5 0.0
0.0 0.5 0.5
0.5 0.0 0.5
1 1
cart
0.00 0.00 0.00
0.50 0.0 0.0

INCAR

##############################################
## Optimum HSE mixing parameter (AEXX) for MgO
## Expt gap = 7.8 eV
## fit gap wrt. 0<AEXX<1
## Compute the bandgap using different value of AEXX 
## in the range (0,1) and find the value which leads 
## to the best agreement with the experimental gap. 
## hint: the gap grows lineraly with AEXX
## Better preconverge with PBE first!
##############################################
    
## Selects the HSE06 hybrid functional
#LHFCALC = .TRUE. ; HFSCREEN = 0.2 ; AEXX=0.25  
#ALGO = D ; TIME = 0.4 
     
## Leave this in
ISMEAR =  0
SIGMA  =  0.01
GGA    = PE

KPOINTS

k-points
0
Gamma
  4  4  4
  0  0  0

Calculation

  • script to extract G-eigenvalues and calculate the bandgap
grep "      4     " OUTCAR | head -8 | \
awk 'BEGIN{i=1}{a[i]=$2 ; i=2} END{for (j=1;j<i;j++) print j,a[j]}' > vband.dat
grep "      5     " OUTCAR | head -8 | \
awk 'BEGIN{i=1}{a[i]=$2 ; i=2} END{for (j=1;j<i;j++) print j,a[j]}' > cband.dat

The bandgap is obainted by substracting the eigenvalues written in cband.dat (conduction band minimum at Gamma) and vband.dat (valence band maximum at Gamma)

Download

5_2_MgO_mixing.tgz