We need only the input file

Input file

MgO_EOS.d12

MGO BULK
CRYSTAL
0 0 0
225
4.26068985
2
 12 0.    0.    0.
  8 0.5   0.5   0.5
EOS
RANGE
0.92 1.08 6
PRANGE
0 50 15
END
END
12 4
0 0 8 2.0 1.0
 68370.0     0.0002226
  9661.0     0.001901
  2041.0     0.011042
   529.6     0.05005
   159.17    0.1690
    54.71    0.36695
    21.236   0.4008
     8.791   0.1487
0 1 5 8.0 1.0
  143.7     -0.00671    0.00807
   31.27    -0.07927    0.06401
    9.661   -0.08088    0.2092
    3.726    0.2947     0.3460
    1.598    0.5714     0.3731
0 1 1 0.0 1.0
    0.688    1.0        1.0
0 1 1 0.0 1.0
    0.28     1.0        1.0
8 4
0 0 8 2.0 1.0
 8020.0    0.00108
 1338.0    0.00804
  255.4    0.05324
   69.22   0.1681
   23.90   0.3581
    9.264  0.3855
    3.851  0.1468
    1.212  0.0728
0 1 4 8.0 1.0
   49.43  -0.00883 0.00958
   10.47  -0.0915  0.0696
    3.235 -0.0402  0.2065
    1.217  0.379   0.347
0 1 1 0.0 1.0
    0.5    1.0     1.0
0 1 1 0.0 1.0
    0.191  1.0     1.0
99   0
END
DFT
CORRELAT
PBE
EXCHANGE
PBE
END
SHRINK
6 6
END

 

Calculation 

/MgO-eos> crystal < MgO_EOS.d12  |tee out

 

Results

NB: The volume value is that of the primitive cell which the 1/4 of the conventional cell volume.

 

At the end of the out file, we find table of volumes vs energies values 


 SORTING VOLUMES/ENERGIES

     VOLUME (A^3)    ENERGY (a.u.)

      17.789658   -2.753025909428E+02
      18.382125   -2.753041931610E+02
      18.987603   -2.753049812670E+02
      19.336585   -2.753050933587E+02
      19.606232   -2.753050221072E+02
      20.238155   -2.753043816197E+02
      20.883512   -2.753031130184E+02

 +++++++ FITTING USING ALL POINTS +++++++

 USERS OF THIS EOS MODULE SHOULD KINDLY CITE THE FOLLOWING REFERENCE:

 A. Erba, A. Mahmoud, D. Belmonte and R. Dovesi, J. Chem. Phys., 140, 124703 (2014)



 EQUATION OF STATE             VOL(A^3)        E(AU)       BM(GPa)   BM PRIME
 -------------------------------------------------------------------------------
 MURNAGHAN 1944                 19.3295      -275.30509221  155.80     3.72
 BIRCH-MURNAGHAN 1947           19.3293      -275.30509261  156.12     3.73
 POIRIER-TARANTOLA 1998         19.3293      -275.30509283  156.29     3.74
 VINET 1987                     19.3293      -275.30509273  156.21     3.74

 POLYNOMIAL FITTING            VOL(A^3)        E(AU)       BM(GPa)
 -------------------------------------------------------------------------------
 THIRD ORDER POLYNOMIAL         19.3291      -275.30509521  158.17
 FOURTH ORDER POLYNOMIAL        19.3291      -275.30509251  156.04
 FIFTH ORDER POLYNOMIAL         19.3285      -275.30509250  156.05
 

We create a file V-E.out with theses values 

     # VOLUME (A^3)    ENERGY (a.u.)

      17.789658   -2.753025909428E+02
      18.382125   -2.753041931610E+02
      18.987603   -2.753049812670E+02
      19.336585   -2.753050933587E+02
      19.606232   -2.753050221072E+02
      20.238155   -2.753043816197E+02
      20.883512   -2.753031130184E+02

and we can plot the results using gnuplotscript script.gnu

set output 'plot.png'

# Key means label...
set key inside bottom right
set xlabel 'Volume (A^3)'
set ylabel 'Energy (a.u.)'
set title 'Some Data'
plot  "V-E.out" using 1:2 title 'Energy-Volume' with linespoints

 

/MgO-eos> gnuplot --persist script.gnu

We can plot the results using gnuplot online


https://gnuplot.respawned.com/#

We can find also some thermodynamical properties according to different EOS. We will present those related to Birch-Murnagham EOS

 THERMODYNAMIC FUNCTIONS OBTAINED AT 0 K WITH EOS: BIRCH-MURNAGHAN 1947     
 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++

 V = VOLUME, P = PRESSURE, E = ENERGY, G = GIBBS FREE ENERGY, B = BULK MODULUS

 V (A^3)   P (GPa)        E (a.u.)            G (a.u.)      B (GPa)

   19.33      0.00      -275.30509261      -275.30509097     156.12
   18.91      3.57      -275.30492358      -275.28943224     169.30
   18.53      7.14      -275.30445844      -275.27409909     182.23
   18.18     10.71      -275.30374850      -275.25906722     194.93
   17.86     14.29      -275.30283276      -275.24430526     207.44
   17.57     17.86      -275.30174237      -275.22979705     219.77
   17.29     21.43      -275.30050197      -275.21552297     231.95
   17.03     25.00      -275.29913149      -275.20146569     243.98
   16.79     28.57      -275.29764786      -275.18761520     255.89
   16.56     32.14      -275.29606435      -275.17395445     267.68
   16.35     35.71      -275.29439278      -275.16047467     279.35
   16.14     39.29      -275.29264314      -275.14716710     290.93
   15.95     42.86      -275.29082376      -275.13402205     302.41
   15.77     46.43      -275.28894180      -275.12103067     313.81
   15.59     50.00      -275.28700373      -275.10818681     325.12

 

For a detailed information about the calculation check the following link:

http://tutorials.crystalsolutions.eu/tutorials/eos/eos_tut.html