MgO optimum mixing: Difference between revisions

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


----
== Task ==
*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.


*KPOINTS
== Input ==
<pre>
k-points
0
Gamma
  4  4  4
  0  0  0
</pre>


*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 60: Line 64:


== 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]]
 
----
{{Template:Hybrid_functionals}}
[[VASP_example_calculations|To the list of examples]] or to the [[The_VASP_Manual|main page]]


[[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