# Rodrigo Freitas - rodrigohb@gmail.com


#-------------------------- Initial Setup -------------------------------------#
  units             metal
  atom_modify       map array 
#------------------------------------------------------------------------------#


#-------------------------- Atomic Setup --------------------------------------#
  lattice           sc 10.0
  region            my_region block 0 8 0 8 0 8
  create_box        1 my_region
  create_atoms      1 box

  mass              * 50.0
  atom_modify       sort 0 0
#------------------------------------------------------------------------------#


#---------------------- Thermostat & Barostat ---------------------------------#
  fix               f1 all nve
  fix               f2 all spring/self 10.0
  fix               f3 all ti/spring 50.0 2000 1000 function 2
  fix               f4 all langevin 100.0 100.0 0.5 1230917 zero yes
#------------------------------------------------------------------------------#


#------------------ Computes, variables & modifications -----------------------#
  compute           Tcm all temp/com
  fix_modify        f4 temp Tcm

  variable          step    equal step
  variable          dU      equal (f_f2-f_f3)/atoms
  variable          lambda  equal f_f3[1]
  variable          dlambda equal f_f3[2]
#------------------------------------------------------------------------------#


#------------------------- Thermo stuff ---------------------------------------#
  thermo            0
  timestep          0.001
#------------------------------------------------------------------------------#


#------------------------- Running the Simulation -----------------------------#
  velocity          all create 200.0 8128481 mom yes rot yes dist gaussian

  # Forward. 
  run               999
  fix               f5 all print 1 "${step} ${dU} ${lambda} ${dlambda}" & 
                    screen no file forward_fl.dat &
                    title '# step dU lambda dlambda'
  run               2001
  unfix             f5

  # Backward.
  run               999
  fix               f5 all print 1 "${step} ${dU} ${lambda} ${dlambda}" & 
                    screen no file backward_fl.dat &
                    title '# step dU lambda dlambda'
  run               2001
  unfix             f5
#------------------------------------------------------------------------------#