# How to let the CNT cool down and plot the correct out-put for temperature versus time?

Dear All,

I have a nanotube in water and I want the nanotube to posses higher temperature than water initially. I need to plot the temperature versus time to observe the rate at which it cools off. (for all these I am using edpd method)

Here is how I do it by setting the initial velocities using velocity command. calculating per bead temperature and using compute reduce to change the temperature to a global value so I can read it via fix ave/time.

Here is my code for better reference:

units lj
dimension 3
boundary p p p
neighbor 0.2 bin
neigh_modify every 1 delay 0 check yes
neigh_modify one 1500

atom_style hybrid edpd full
bond_style harmonic
angle_style harmonic
pair_style edpd 1.58 9872598

region mybox block -15 15 -15 15 -15 15 units box

create_atoms 2 random 16000 276438 NULL

include parmcnt.lammps
bond_coeff 1 2000 0.77
bond_coeff 2 180 1.9607888988921507

#GROUPING
group CNT type 1
group liquid type 2

#set atom * edpd/temp 1.0

#APPROXIMATE HEAT CAPACITY FOR CNT AND WATER

set atom 1 edpd/cv 0.2E5
set atom 2 edpd/cv 1.0E5

comm_modify vel yes cutoff 5

#RECENTER THE CNT

variable CNT_xcm equal -1xcm(CNT,x)
variable CNT_ycm equal -1
xcm(CNT,y)
variable CNT_zcm equal -1*xcm(CNT,z)
displace_atoms CNT move {CNT_xcm} {CNT_ycm} \${CNT_zcm}

#CHANGE BOX BOUNDARIES

change_box all x final -15 15 y final -15 15 z final -15 15

#PRINT ATOM COORDINATES EVERY 1000 STEPS

dump mydmp all atom 1000 dump.lammpstrj

#SETTING INITIAL VELOCITIES/TEMPERATURES FOR CNT AND WATER

velocity liquid create 0.9 432982 loop local dist gaussian
velocity CNT create 2 432982 loop local dist gaussian

#MOLECULAR DYNAMICS

compute mythermo all temp

thermo 100
thermo_modify temp mythermo
thermo_modify flush yes

###(updates the per-atom temperature, in addition to position and velocity, and must be used with ########the pair_style edpd command)

fix mvv all mvv/edpd 0.5

#OUTPUT TEMPERATURE PER TIMESTEP

compute temp CNT edpd/temp/atom
compute alltemp CNT reduce max c_temp
fix tmppertim CNT ave/time 1 50 50 c_alltemp file tempcnt1.profile

thermo_style custom step temp etotal c_alltemp

timestep 0.01
run 10000

The plot I am getting is:

but this nowhere near cooling off. could you please help me understand what I am doing wrong? is outputting the wrong data or basically the way I am initializing the velocities and let the system reach equilibrium?

Thank you so much