# [lammps-users] Calculation of the diffusion/activation energy

I am using the LAMMPS version 29Oct2020. I am currently attempting to do a KMC simulation to calculate the diffusion coefficient of an Inconel-Ni alloy using LAMMPS. As a part of that, I would like to know how to calculate, in LAMMPS, the diffusion/activation energy that is taken or expended by all the atoms at any given timestep in the model when they diffuse from their current atomic site to a new atomic site. Could anyone provide any insight into this? Thank you.

Regards,
Rajesh

If you want to learn how to compute some property, you look at the software last. Rather you would talk to your adviser(s)/tutor(s), check out relevant textbooks and the published literature to find discussions and explanations of the methodology. Only after that you can look into what you need to compute specifically and how to realize this with different software packages. Looking at the software first is reversing the process and rarely successful (there has to be a ready-to-use tutorial for that).

Hello Dr. Kohlmeyer,

Thank you for your response. I am actually following the methodology given in the paper ‘Yang, Xue, and Wasiu O. Oyeniyi. “Kinetic Monte Carlo simulation of hydrogen diffusion in tungsten.” Fusion Engineering and Design 114 (2017): 113-117.’ to calculate the self-diffusion coefficient of Nickel using the Kinetic Monte Carlo method. I read other papers and PDF articles, from where I found out that to calculate the activation energy from the Arrhenius equation, the value of the jump frequency (k) or the values of the diffusion coefficient (D) and the frequency factor (D_0) should be known. Since I am trying to calculate the self-diffusion coefficient of Nickel from the Arrhenius equation (to calculate the elapsed time as per the aforementioned paper), I require the value of the activation energy of the atoms at every diffusion timestep.

Regards,
Rajesh

You are basically just repeating your previous question here and thus my advice is the same as well.