can LAMMPS compute electrical conductivity, similarly to mean-square displacement

Hello LAMMPS community,

I came across this paper,

Levesque, Maximilien, et al. “Structure and dynamics in yttrium-based molten rare earth alkali fluorides.” The Journal of chemical physics 138.18 (2013): 184503.

and found the Equation (2) to compute the electrical conductivity,Screenshot from 2016-12-01 12-50-41.png
This equation is very similar with the Einstein-Smoluchowski relation, which relates the self-diffusivity coefficient to mean-square displacement of MD simulation
Screenshot from 2016-12-01 12-50-28.png

My question is how can I compute the quantities in Equation (2) in LAMMPS? Is there an analogous compute for atomistic charges, as in ‘compute msd’ command at http://lammps.sandia.gov/doc/compute_msd.html? Please let me know if so.

Many thanks,
Anh Tran

No, I think you’d have to write a new compute for that,

or add an optional keyword to compute msd to include

a “multiply by q” for each atom in the summation.

Steve

Screenshot from 2016-12-01 12-50-41.png

Screenshot from 2016-12-01 12-50-28.png

Steve,

Thank you for
​your
reply.​T
hat’s a good idea. I think I’m just going to write a new compute based on compute_msd.h/.cpp, but before I proceed, would you please confirm that I can simply change the keyword from this line of the header file compute_msd.h, and name of the class in C++, and start adding code in the corresponding .cpp file?

Screenshot from 2016-12-01 12-50-41.png

Screenshot from 2016-12-01 12-50-28.png