Example: ReaxFF: ADF geometry optimization using ReaxFF forces

Download reaxff_optimization.run

Expert Option

An example of ADF optimization using ReaxFF forces.

cp "$ADFHOME/atomicdata/ForceFields/ReaxFF/CuCl-H2O.ff" ffield

cat  control << eor
# General parameters
      0 itrans
      1 icentr     0: off, 1: put center of mass at center of cube, 2: put com at origin
      0 imetho     Normal MD-run 1: Energy minimization
      5 igeofo     5: read from adf-provided file, calc forces and stop
      0 timing     0: no timing, 2: timing details
  250.0 axis1      a cell axis
  250.0 axis2      b cell axis
  250.0 axis3      c cell axis
 90.000 angle1     cell angles
 90.000 angle2     cell angles
 90.000 angle3     cell angles
     25 irecon     Frequency of reading control-file
      5 ixmolo     xmolout 0: xyz only, 1: xyz + vels + molnr, 2: xyz + mol.nr, 5: xyz + bonds
      1 ichupd     Charge update frequency
      4 icharg     always 4: Full system EEM
 298.00 mdtemp     MD-temperature (K), unless tregime file is present
  100.0 tdamp1     1st Berendsen/Anderson temperature damping constant (fs)
# MD-parameters
      1 imdmet     MD-method. 1:Velocity Verlet+Berendsen 2:Hoover-Nose (again NVT); 3:NVE 4:NPT
  0.250 tstep      MD-time step (fs)
   0.00 mdpres     MD-pressure (GPa)
  500.0 pdamp1     Berendsen pressure damping constant (fs)
      0 inpt       0: Change all cell parameters in NPT-run  1: fixed x 2: fixed y 3: fixed z
      1 nmdit      Number of MD-iterations
      5 iout1      Output frequency to unit 71 and unit 73
   5000 iout2      Save coordinates (xmolout, moldyn.vel, Molfra)
      1 iout3     Create moldyn.xxx files (0: yes, 1: no)
      0 ivels      0: Use velocities from vels restart-file; 1: Zero initial velocities
   2000 iout6      Frequency of molsav.xxxx restart file creation (xyz, vels and accel)
     50 iout7      Frequency of reaxout.kf writing
     25 irten      Frequency of removal of rotational and translational motions
      0 npreit     Nr. of iterations in previous runs
   0.00 range      range for back-translation of atoms outside periodic box
# MM-parameters
1.00000 endmm      End point criterium for MM energy minimization (force)
      0 imaxmo     0: conjugate gradient, -1: temperature dependent MD minimization (with imethod 1)
      1 imaxit     Maximum number of iterations
      1 iout4      Frequency of structure output during minimization
      0 icelop     0 : no cell opt, 1: numerical cell opt
1.00010 celopt     Cell parameter change factor
      0 icelo2     0: Cubic cell optimization; 1/2/3: only a/b/c; 4: c/a ratio
eor

$ADFBIN/adf << eor
ATOMS
O                   9.21547  18.20279   5.17255
H                   9.82360  18.92182   4.93781
H                   9.54331  17.44166   4.66744
O                   4.62358  16.65456  21.14691
H                   3.99888  17.39042  21.24792
H                   5.47889  17.03353  21.40531
O                  21.12941   6.02920   5.89396
H                  21.47696   6.74566   6.44878
H                  20.69255   5.43353   6.52347
END
GEOMETRY
    branch New
    optim cartesian
    iterations 1000
    ExternProgram "sh $ADFBIN/reax2adf" coord=adf_reaxff.coords energy=adf_reaxff.energy grad=adf_reaxff.grad
END
Basis
End
end input
eor