input.lammps

# This LAMMPS input script simulates a water ethanol mixture with salt
# Written by Simon Gravelle (https://simongravelle.github.io/)
# Find more scripts here: https://github.com/simongravelle/lammps-input-files
# LAMMPS tutorials for beginners: https://lammpstutorials.github.io/

units real
atom_style full
bond_style harmonic
angle_style harmonic
dihedral_style opls
boundary p p p
pair_style lj/cut/tip4p/long 3 4 1 1 0.105 12.0
kspace_style pppm/tip4p 1.0e-5
special_bonds lj 0.0 0.0 1.0 coul 0.0 0.0 1.0
pair_modify mix arithmetic

region box block -24 24 -24 24 -24 24
create_box 10 box &
bond/types 5 &
angle/types 6 &
dihedral/types 4 &
extra/bond/per/atom 20 &
extra/angle/per/atom 20 &
extra/special/per/atom 20 &
extra/dihedral/per/atom 20

include parm.lammps

molecule h2omol ../LAMMPS-molecules/water_H2O/tip4p-2005.mol offset 2 0 0 0 0
molecule ethmol ../LAMMPS-molecules/ethanol_C2H5OH/OPLS.mol offset 4 1 1 0 0

create_atoms 1 random 20 704220 NULL overlap 1.5 maxtry 1000
create_atoms 2 random 20 104769 NULL overlap 1.5 maxtry 1000
create_atoms 0 random 200 654312 NULL mol ethmol 36597 overlap 1.5 maxtry 1000
create_atoms 0 random 400 456415 NULL mol h2omol 454756 overlap 2 maxtry 1000

set type 1 charge 1
set type 2 charge -1

group nacl type 1:2
group water type 3:4
group ethnl type 5:10

dump mydmp all atom 1000 dump.lammpstrj
thermo 2000

fix mynve all nve/limit 0.1
fix myber all temp/berendsen 300 300 100
fix myshk all shake 1.0e-5 200 0 b 1 a 1

run 2000

unfix mynve
unfix myber

fix mynpt all npt temp 300 300 100 iso 1 1 1000

run 50000

write_data water-ethanol.data