MgO optimum mixing: Difference between revisions

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{{Template:Hybrid_functionals}}
{{Template:Hybrid_functionals - Tutorial}}
 
== Task ==
 
Find optimum HSE mixing parameter for MgO.


Description: find optimum HSE mixing parameter for MgO
== Input ==


----
=== {{TAG|POSCAR}} ===
*{{TAG|INCAR}}
<pre>
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
</pre>
 
=== {{TAG|INCAR}} ===
  ##############################################
  ##############################################
  ## Optimum HSE mixing parameter ({{TAGBL|AEXX}}) for MgO
  ## Optimum HSE mixing parameter ({{TAGBL|AEXX}}) for MgO
Line 16: Line 32:
  ##############################################
  ##############################################
      
      
  ## Selects the HSE06 hybrid function
  ## Selects the HSE06 hybrid functional
  #{{TAGBL|LHFCALC}} = .TRUE. ; {{TAGBL|HFSCREEN}} = 0.2 ; {{TAGBL|AEXX}}=0.25   
  #{{TAGBL|LHFCALC}} = .TRUE. ; {{TAGBL|HFSCREEN}} = 0.2 ; {{TAGBL|AEXX}}=0.25   
  #{{TAGBL|ALGO}} = D ; {{TAGBL|TIME}} = 0.4  
  #{{TAGBL|ALGO}} = D ; {{TAGBL|TIME}} = 0.4  
Line 25: Line 41:
  {{TAGBL|GGA}}    = PE
  {{TAGBL|GGA}}    = PE


*{{TAG|KPOINTS}}
=== {{TAG|KPOINTS}} ===
<pre>
<pre>
k-points
k-points
Line 34: Line 50:
</pre>
</pre>


*{{TAG|POSCAR}}
== Calculation ==
<pre>
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
</pre>


*script to extract G-eigenvalues and calculate the bandgap
*script to extract G-eigenvalues and calculate the bandgap
Line 59: 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]]
----
[[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