Thermostate atoms

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1

Dear Dr. Alex

Thank you so much for your help and also for your quick response.

I simulate the buckling of CNT under the radial pressure through displace atoms in middle section of tube (group 1) with fixed boundary conditions at the two ends of CNT (group 2 &3 with five and eight raw of atoms at two ends of CNT), as below:

label looplable

displace_atoms 2 move 0 0 0 units box

displace_atoms 3 move 0 0 0 units box

displace_atoms 1 move v_x2 v_y2 0 units box

fix 2 1 nvt temp 300 300 0.01

thermo_style custom step temp vol pe press v_y1 v_x1

run 5000

next Nstep

jump in.cnt looplable

(Note that there are 2208 atoms in this simulation of CNT which 1896 atoms are in group 1 and 120 and 192 residual atoms are in group 2 &3)

I dont know which section of CNT should be considered to impose nvt command on its atoms. When I impose nvt on middle section of CNT (group1), as:

fix 2 1 nvt temp 300 300 0.01

the buckling does not take place because through nvt command the pressure is removed.
Please help me.
Thank you.

2

Dear Dr. Alex
Thank you so much for your help and also for your quick response.

I simulate the buckling of CNT under the radial pressure through displace
atoms in middle section of tube (group 1) with fixed boundary conditions at
the two ends of CNT (group 2 &3 with five and eight raw of atoms at two
ends of CNT), as below:

​this is not really a question about ​LAMMPS, but about your research. this
is something your should discuss with your adviser and your collaborator.
this mailing list is no replacement for that. i for one have no interest in
your field of research and/or to fill in for your adviser.

there is just one question about this in general: why use a thermostat at
all? what does your CNT exchange energy with? and how?

axel.

3

I only want to relax CNT after imposing radial pressure through using nvt command.