### DEFINE SIMULATION BOX GEOMETRY ###
lattice sc 0.2
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 2.8
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 atoms
thermo 10

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

### SPECIFY TIMESTEP ###

### 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} 
unfix nvt
fix nve all nve
run 10000
reset_timestep 0

### MEASURE SYSTEM STATE ###
thermo_style custom step etotal temp vol density
variable dens equal density
variable temp equal temp
variable temp2 equal temp*temp
variable vol equal vol
variable etot equal etotal
variable etot2 equal etotal*etotal
variable N equal atoms
variable N2 equal atoms*atoms
fix aves all ave/time 100 1000 100000 v_temp v_etot v_etot2
run 100000

### AVERAGES ###
variable avetemp equal f_aves[1]
variable avetemp2 equal f_aves[1]*f_aves[1]
variable aveetot equal f_aves[2]
variable aveetot2 equal f_aves[3]
variable aveetotl equal f_aves[2]*f_aves[2]



### HEAT CAPACITY CALCULATION ###
variable Cv equal ${N2}*((${aveetot2}-${aveetotl})/${avetemp2})
variable CvV equal ${Cv}/${vol}

### PRINT ###
print "Averages"
print "--------"
print "Cv: ${Cv}"
print "CvV: ${CvV}"