&FORCE_EVAL
 METHOD FIST
 &MM
  &FORCEFIELD
   &SPLINE
    EPS_SPLINE 1.0E-8
   &END
   &NONBONDED
    &TERSOFF
     ATOMS Si Si
     A        1.8308E3
     B        4.7118E2
     lambda1  2.4799
     lambda2  1.7322
     alpha    0.00
     beta     1.0999E-6
     n        7.8734E-1
     c        1.0039E5
     d        1.6218E1
     h       -5.9826E-1
     lambda3  1.7322
     bigR     2.85
     bigD     0.15
     RCUT    10.0
    &END TERSOFF
   &END NONBONDED
  &END FORCEFIELD
  &POISSON
   &EWALD
    EWALD_TYPE none
   &END EWALD
  &END POISSON
 &END MM
 &SUBSYS
  &CELL
   PERIODIC XYZ
   A 2.7 0.0 2.7
   B 0.0 2.7 2.7
   C 2.7 2.7 0.0
   MULTIPLE_UNIT_CELL 2 2 2
  &END CELL
  &TOPOLOGY
   MULTIPLE_UNIT_CELL 2 2 2
   CONNECTIVITY OFF
  &END TOPOLOGY
  &COORD
   Si  0.00  0.00  0.00
   Si  1.35  1.35  1.35
  &END COORD
  &PRINT
   &ATOMIC_COORDINATES
   &END
   &CELL
   &END
  &END
 &END SUBSYS
 STRESS_TENSOR ANALYTICAL
 &PRINT
  &STRESS_TENSOR
  &END STRESS_TENSOR
 &END PRINT
&END FORCE_EVAL
&GLOBAL
 PROJECT Si_direct_cell_opt
 RUN_TYPE CELL_OPT
&END GLOBAL
&MOTION
 &CELL_OPT
  OPTIMIZER BFGS
 &END CELL_OPT
 &GEO_OPT
  OPTIMIZER BFGS
  &BFGS
   TRUST_RADIUS 0.1
  &END BFGS
 &END GEO_OPT
 &PRINT
  &CELL on
  &END CELL
  &RESTART on
   BACKUP_COPIES 0
  &END RESTART
  &RESTART_HISTORY off
  &END RESTART_HISTORY
 &END PRINT
&END MOTION
