in.front

# Example script of liquid front propagation in glass 2d-NPT simulation
# see C. Herrero et al. ( https://doi.org/10.48550/arXiv.2210.04775 ) for details

# parameters set

variable	Ti equal 0.035		# Initial glass temperature
variable        Ta equal 0.11		# Annealing temperature
variable	P equal 2.31052		# Pressure
variable 	wx equal 80		# half slit size
variable	seed equal 4115699	# RNG seed

# problem setup

units           lj
atom_style      charge
atom_modify 	map array

dimension 	2

pair_style      lj/polysoft 2.03
read_data       Ti${Ti}.lmps		# initial glass config equlibrated with swap MC
pair_coeff      1 1 1.0 1.0 2.025 1.25 0.2

neighbor        0.3 bin
neigh_modify    every 1 delay 0 check yes

# define liquid (front) and glass regions
region		front block -${wx} +${wx} INF INF INF INF
group		front dynamic all region front
region 		glassL block INF -${wx} INF INF INF INF
region		glassR block +${wx} INF INF INF INF INF
region		glass union 2 glassL glassR
group		glass dynamic all region glass

velocity 	all create ${Ti} ${seed}

timestep        0.01
reset_timestep  0

# Perform simulation
# 1st let the system expand quickly

fix             1 all npt temp ${Ta} ${Ta} 1.0 iso $P $P 1.0

# track glass and front pressure
compute		peratomf front stress/atom NULL
compute		pf front reduce sum c_peratomf[1] c_peratomf[2]
variable	pressf equal -(c_pf[1]+c_pf[2])/(2*2*v_wx*ly)

compute         peratomg glass stress/atom NULL
compute         pg glass reduce sum c_peratomg[1] c_peratomg[2]
variable        pressg equal -(c_pg[1]+c_pg[2])/(2*(lx-2*v_wx)*ly)

compute         tempf front temp
compute         tempg glass temp

variable	thermofreq equal logfreq2(100,18,10)
thermo          v_thermofreq
thermo_style    custom step temp pe ke etotal press vol v_pos v_pressf c_tempf v_pressg c_tempg
thermo_modify   flush yes

run             100000

# 2nd freeze all the particles and create liquid front of size 2*wx

unfix 		1
fix		1 front nvt temp 0.8 0.8 1.0

run		100000

# 3rd equilibrate the liquid inside the cavity at Ta (only with md in this example)

unfix		1
fix		1 front nvt temp ${Ta} ${Ta} 1.0

run		1000000

# 4th study front propagation from this configuration

unfix		1
reset_timestep	0

velocity	all create ${Ta} ${seed} rot yes dist gaussian

fix		1 all npt temp ${Ta} ${Ta} 1.0 iso $P $P 1.0

dump		traj all custom 500000 front.lammpstrj x y c_epot c_patom[1] c_patom[2] c_patom[4]
dump_modify	traj sort id first yes pbc yes

restart         5000000 front.*.restart

run             10000000

write_data      front.end