[lammps-users] about the command minimize

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1

Hello all

I have formed the carbon nanotube coordination data, and I want to do some tension and bending test of this CNT. Do I need first relax this nanotube by using the minimize command to minimize the potential before doing the simulation? I have a doubt for example I checked the C-C distance in nanotube is 1.42A before minimize, and after minimize it becomes 1.499A. I am perplexed the real C-C distance is 1.42A for CNT in many references (e.g. carbon nanotubes and related structures by Peter J.F. Harris Cambridge university press 1999)
And I used the potential from second table of “Empirical potential for hydrocarbons for use in simulating the chemical vapor deposition of diamond films” Donald W. Brenner Physical Review B, Volume 42, Number 15, 9458-9471, November 15, 1990.

Thanks

Anderson

2

hi all,

I just want to average some thermodynamics parameters during simulations.

I tried the following command as the same of the docs provied:

fix 1 all ave/time 100 5 1000 myTemp thermo_temp file temp.profile
fix 1 all ave/time 100 5 1000 c_thermo_press[2] ave window 20

but the error is: “Illegal fix ave/time command”

I dont know why it keep giving me this error message, since thermo_temp is predefined by default when LAMMPS start up.

Is it because I am not using the latest version? I use the oct,07 version.

Stongly suggest Developer give more examples on how do the stastisics with the various commands. That way would be more straitforward. Sometimes the manual is not working very good and is confusing, as far as I am concerned.

AC

3

Assuming you're using the AI-REBO potential, send an email to
Ase Henry (ase at mit.edu) who authored it and see what he says
about this.

Steve

4

You're not using the current version, either of the manual or
maybe the code.

Look at the same example on the WWW page manual and you'll
see that it's different. You need c_thermo_temp. If you tell
me something that isn't clear on the doc page, I'll change it. But
I think it's pretty clear.

Steve