[lammps-users] question on MEAM and Tersoff

Hello everyone,

I was wondering if anybody has experience in using MEAM or Tersoff potentials for 3C SiC.
I’m trying to obtain the dispersion relation for SiC but I find that the optical phonon
modes predicted with MEAM SiC have much higher magnitudes than those in the literature.
When I try the Tersoff potential I find that in a constant energy run the energy of the
system drifts considerably.

Any suggestions are appreciated.

Jaime Sanchez

You'd need to ask Greg Wagner (gjwagne at sandia.gov) about
MEAM. Re: Tersoff - I don't know of any issue that would
cause a different energy drift than any other potential.
Is your timestep sufficiently small?



For the Tersoff potential I considered a timestep of 1 fs. Should it be smaller? What I found is that after rescaling the velocities of the atoms for a long time, then releasing the fix and just continue with nve integration, the temperature rises considerably. I also tried using a fix tether to prevent drift of the COM but that didn’t help.