[lammps-users] Local thermal equilibrium

Dear All

I am running a heat transfer case by generate a thermal gradient in my system using Lammps. In order to get the temperature profile in my domain, I divide my liquid argon domain into 100 bins. I got good results and submit the paper to be published. But the reviewers ask me a question that how I can demonstrate each bin size has local thermal equilibrium so that I can define the local temperature. Can anybody give me some suggestion about how to answer this question correctly?

Thanks very much!


In a similar situation, we computed the velocity distribution in each bin and demonstrated it was boltzmann with the correct distribution for the bin temperature.

Hi Ziyuan,

You should do more on this work to make it published if you don’t understand the basic principle of non-equilibrium molecular dynamics. Actually,

“the main challenge in performing NEMD simulations is to choose a suitable thickness or the total number of atoms in sample sections in order to establish local thermal equilibrium and calculate the local temperature. In quantum mechanics systems, thermal equilibrium is established by the anharmonic coupling of the vibrational normal modes, or phonon–phonon scattering. The key relevant quantity is the total number of phonon–phonon scattering events per section during the entire simulation run.” “Previous work found that ∼30 atoms in one section are adequate for equilibrium in which the velocity distribution of atoms follows the Maxwell–Boltzmann distribution.”
-----From my own paper Xiaopeng Huang et al., “Thermal transport in Si/Ge nanocomposites”, J. Phys. D: Appl. Phys. 42 (2009) 095416.

You can read the paper for more details or you can search “local thermal equilibrium” in several academic databases. You will learn a lot.