View source for VASP Example: Calculate Energy-Lattice Parameter curve for MnBiNi

The necessary tools to perform the basic calculations to investigate the  lattice parameter for MnBiNi and the cohesive energy determination have been shown in this page.
We need at least 4 input files and one file has the secript for your calculation

<font color="red"> Note: The page is under a continuous developing stage. </font>

==== POSCAR ====
The file (position card) defines the box size corresponding to the near equilibrium fcc lattice structure of one al atom:

<pre>
MnBiNi
5.28
 0.500 -0.866 0.000
 0.500 0.866 0.000
 0.000 0.000 1.45
 2 2 2
direct
 0.0000 0.0000 0.0000   Mn 1
 0.0000 0.0000 0.5000   Mn 2
 0.3333 0.6667 0.2500   Bi 3
 0.6667 0.3333 0.7500   Bi 4
 0.3333 0.6667 0.7500   Ni 5
 0.6667 0.3333 0.2500   Ni 6

</pre>

==== POTCAR ====
The Potential Card can be downloadable from: /usr/local/vasp/
Depending on which potential you would like to use, go to:
* PAW (Projected augmented wave), 
* PAW-GGA (Projected augmented wave-generalized gradient approximation), 
* PS (Pseudopotential) etc.

<font color="red"> To access these files you need to be a member of vasp group. There are four sub-folders: pot, pot_GGA, potpaw, and potpaw_GGA at /usr/local/vasp/.</font>


==== KPOINTS ====
The number of nodal points to calculate the solution; in mesh refinement the greater the number the better the answer but is more costly
<pre>
4x4x4            Comment
 0               0 = automatic generation of k-points
Monkhorst        M use Monkhorst Pack
 4 4 4           grid 4x4x4
 0 0 0           shift (usually 0 0 0)


</pre>


==== INCAR ====
Input Card to solve the Schrodinger Equation
<pre>
LWAVE = .FALSE.
LCHARG = .FALSE.
LREAL = .FALSE.
ADDGRID = .TRUE.
PREC = Accurate
EDIFF = 1e-05
ENCUT = 400.0000
ALGO = Fast
#NBANDS = 168
IBRION = 1
LMAXMIX = 4
LDAU= .TRUE.
LDAUTYPE = 2
LDAUL = 2 -1 2
LDAUU = 6.0 0.0 5.0
LDAUJ = 1.0 0.0 1.0
ISPIN=2
VOSKOWN=1
LORBIT=11
MAGMOM = 2*4 2*0 2*2
ISIF =3
</pre>

==== Script ====
<pre>

rm WAVECAR
for i in 1.2 1.3 1.4 1.5 1.6 1.7 1.8 1.9 2.0 2.1 2.2 2.3 2.4 2.5 2.6 2.7 2.8 2.9 3.0 3.1 3.2 3.3 3.4 3.5 3.6 3.7 3.8 3.9 4.0 4.1 4.2 4.3 4.4 4.5 4.6 4.7 4.8 4.9 5.0 5.1 5.2 5.3 5.4 5.5 5.6 5.7 5.8 5.9 6.0  
do
cat >POSCAR <<!
MnBiNi
$a
 0.500 -0.866 0.000
 0.500 0.866 0.000
 0.000 0.000 1.45
 2 2 2
direct
 0.0000 0.0000 0.0000   Mn 1
 0.0000 0.0000 0.5000   Mn 2
 0.3333 0.6667 0.2500   Bi 3
 0.6667 0.3333 0.7500   Bi 4
 0.3333 0.6667 0.7500   Ni 5
 0.6667 0.3333 0.2500   Ni 6
!
echo "a=$i" ; vasp_5212_talon
E=`tail -1 OSZICAR` ;echo $i $E >> SUMMARY.fcc
done
cat SUMMARY.dat
</pre>

=== Result ===
we got diffrent output files and for our gole here we make file named SUMMARY.dat from the scrip. Summery file should have two comunt one for diffrent lattice parmeter and the other for the energy . We plot this data. 
</pre>

[[image:E-A_MnBiNi.png|thumb|center|450px|Figure 1. Energy Vs Lattice parameter for MnBiNi.]]
Where the lattice parameter A0 = 4.52 Angstrom. Cohesive energy Emin = -2.659   eV.

for more sources of input files you can looking for matrial project *[https://materialsproject.org/]

[[Category:Electronic Scale]]
[[Category:VASP]]