About the NVT ensemble

LAMMPS LAMMPS Beginners
1

Dear LAMMPS users,

Recently I followed the simulation procedures in a literature. In this literature, NVT ensemble is employed. Also, the thermostat is through the Bussi thermostate (temp/csvr). I have the following questions.

#1 In the mannual, I have learned that the temp/csvr does not integrate the position of atoms, and thus a separate time integration fix should be used. I have used the NVE according to the mannual. My question is: Is the NVE + Bussi thermostat(temp/csvr) = NVT.

#2 In the literature, the relaxation constant is 0.1 ps. So which parameter is relative to this relaxation constant in the command temp/csvr. I have seen in some topics in the community and perhaps the Tdamp corresponds to the relaxation constant.

Thanks for your help!
Best regards,
Shusen Guo

2

Hello,

  • #1 This is correct for some systems, but as stated in this forum before, using fix NVE + a thermostat (or fix NVT) does not enforce the NVT ensemble.

  • #2 Yes indeed, “the Tdamp parameter is specified in time units and determines how rapidly the temperature is relaxed”, from the csrv page.

Best,
Simon

3

Hello Simon,
Really appreciate for your kindly help. This really solves my problems!

Best regards,
Shusen Guo