input.lammps

# LAMMPS input script by Simon Gravelle
# This input is part of a tutorial from https://lammpstutorials.github.io
# Last tested using the 2Aug2023 stable LAMMPS version
# This file was released under the GNU general public license v3.0

units real
atom_style full

read_data water_init.data

pair_style reaxff NULL safezone 3.0 mincap 150
pair_coeff * * qeq_ff.water O H

neighbor 1 bin
neigh_modify every 1 delay 0 check yes

# define groups 
group gO type 1
group gH type 2

# help the qeq/reax by setting reasonable charge from the start
set group gO charge -1
set group gH charge 0.5

# initial dynamics with small timestep (because of box change during NPT)
fix mynve all nve/limit 0.1 
fix myber all temp/berendsen 1 360 1
fix myqeq all qeq/reax 1 0.0 10.0 1e-6 param.qeq.reax
fix myspr gO spring/self 5.0 # maintain the oxygen in place
timestep 0.25

include output.lammps

# first short equilibration
run 10000
unfix mynve
unfix myber

# use langevin thermostating
fix mynve all nve
fix mylng all langevin 360 360 23.0 694835

run 500000