### DEFINE SIMULATION BOX GEOMETRY ###
variable dens equal 0.2
lattice sc ${dens}
region box block 0 15 0 15 0 15
create_box 1 box
create_atoms 1 box

### DEFINE PHYSICAL PROPERTIES OF ATOMS ###
mass 1 1.0
pair_style lj/cut/opt 3.0
pair_coeff 1 1 1.0 1.0
neighbor 2.0 bin

### SPECIFY THE REQUIRED THERMODYNAMIC STATE ###
variable T equal 2.0
variable timestep equal 0.0025

### ASSIGN ATOMIC VELOCITIES ###
velocity all create ${T} 12345 dist gaussian rot yes mom yes

### SPECIFY ENSEMBLE ###
timestep ${timestep}
fix nve all nve

### THERMODYNAMIC OUTPUT CONTROL ###
thermo_style custom time etotal temp press
thermo 10

### RECORD TRAJECTORY ###
dump traj all custom 1000 output-1 id x y z

### RUN SIMULATION TO MELT CRYSTAL ###
run 10000
unfix nve
reset_timestep 0
 
### BRING SYSTEM TO REQUIRED STATE ###
variable tdamp equal ${timestep}*100
fix nvt all nvt temp ${T} ${T} ${tdamp} 
run 10000
reset_timestep 0

### SWITCH OFF THERMOSTAT ###
unfix nvt
fix nve all nve

### MEASURE SYSTEM STATE ###
thermo_style custom etotal temp atoms vol
variable temperature equal temp
variable temperaturesqd equal temp*temp
variable volume equal vol
variable energy equal etotal
variable energysqd equal etotal*etotal
variable atoms equal atoms 
variable atomssqd equal atoms*atoms 
fix aves all ave/time 100 1000 100000 v_temperature v_energy v_energysqd v_temperaturesqd
run 100000

variable avtemperature equal f_aves[1]
variable avenergy equal f_aves[2]
variable avenergysqd equal f_aves[3]
variable avtemperaturesqd equal f_aves[4]

variable heatcapacity equal ${atomssqd}*(${avenergysqd}-(${avenergy}*${avenergy}))/${avtemperaturesqd}

print "Averages"
print "--------"
print "Temperature: ${avtemperature}"
print "Number of Atoms, N: ${atoms}"
print "Volume: ${volume}"
print "Heat Capacity: ${heatcapacity}"