We need only the input file

Input file

MgO.opt

MGO BULK - CELL OPT
CRYSTAL
0 0 0
225
4.217
2
12 0.    0.    0.
8 0.5   0.5   0.5
OPTGEOM
CELLONLY
END
END
12  3
0  0  8  2.  1.
68371.875      0.0002226
9699.34009    0.0018982
2041.176786   0.0110451
529.862906   0.0500627
159.186000   0.169123
54.6848     0.367031
21.2357     0.400410
8.74604    0.14987
0 1 6 8. 1.
156.795  -0.00624  0.00772
31.0339  -0.07882  0.06427
9.6453   -0.07992  0.2104
3.7109    0.29063  0.34314
1.61164   0.57164  0.3735
0.64294   0.30664  0.23286
0 1 1 0. 1.
0.4       1.       1.
8 3
0 0 8 2. 1.
4000.    0.00144
1355.58  0.00764
248.545  0.05370
69.5339  0.16818
23.8868  0.36039
9.27593  0.38612
3.82034  0.14712
1.23514  0.07105
0 1 5 8. 1.
52.1878 -0.00873  0.00922
10.3293 -0.08979  0.07068
3.21034 -0.04079  0.20433
1.23514  0.37666  0.34958
0.536420 0.42248  0.27774
0 1 1 0. 1.
0.210000 1.  1.
99 0
END
SHRINK
8 8
FMIXING
30
END

Calculation 

/MgO-eos> crystal < MgO.opt  |tee out

 

Results

At the end of the out file, we find the optimized lattice parameter and volume of the conventional cell and the primitive cell.

The input lattice parameter value is  4.217 A


CRYSTALLOGRAPHIC CELL (VOLUME=         73.59363288)
         A              B              C           ALPHA      BETA       GAMMA 
     4.19063736     4.19063736     4.19063736    90.000000  90.000000  90.000000

 

 

LATTICE PARAMETERS (ANGSTROMS AND DEGREES) - BOHR = 0.5291772083 ANGSTROM
 PRIMITIVE CELL - CENTRING CODE 5/0 VOLUME=    18.398408 - DENSITY  3.608 g/cm^3
         A              B              C           ALPHA      BETA       GAMMA 
     2.96322810     2.96322810     2.96322810    60.000000  60.000000  60.000000

 

CONVERGENCE TESTS SATISFIED AFTER   4 ENERGY AND GRADIENT CALCULATIONS

 ******************************************************************
 * OPT END - CONVERGED * E(AU):  -2.746642754228E+02  POINTS    4 *
 ******************************************************************

   BAND GAP:                     19.9686  eV