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The .geom file

The <seedname>.geom file contains a brief record of the main results at the end of each BFGS step. Note that everything in the .geom file is in atomic units. So, for example, the end of BFGS iteration 0 would correspond to the following output in the .geom file

              -7.93316351E+000     -7.93316351E+000                       <-- E
               0.00000000E+000      5.13126785E+000      5.13126785E+000  <-- h
               5.13126785E+000      0.00000000E+000      5.13126785E+000  <-- h
               5.13126785E+000      5.13126785E+000      0.00000000E+000  <-- h
 Si     1      0.00000000E+000      0.00000000E+000      0.00000000E+000  <-- R
 Si     2      7.56877069E+000      2.52292356E+000      7.56877069E+000  <-- R
 Si     1     -5.22300739E-003      6.43530285E-003     -1.71774942E-003  <-- F
 Si     2      5.22300739E-003     -6.43530285E-003      1.71774942E-003  <-- F

The first line contains the iteration number. The next line is the final energy in Hartrees (1eV = 0.03674 932 45 Ha). This is repeated twice - why? In a finite pressure calculation it is the free energy, the enthalpy, that is minimised. This is E + PV where E is the energy, P is the pressure and v is the volume. In this case P = 0 so the energy and the enthalpy are the same. The final energy is listed first and then the enthalpy.

The next three lines are the unit cell vectors in cartesian coordinates in units of Bohrs. There exist programs such as geom2xyz to convert the .geom file into a list of xyz coordinates. For each atom in the supercell the absolute position is listed and then the forces are listed (both quantities in atomic units).