Hello,

I’m currently trying to set up a simulation for PVDF with values reported in a research paper. I have a question about the dihedral_style nharmonic command. The paper that I’m referencing shows a dihedral equation:

E = Sum(n=0,n) An*cos[n*phi] Eqn. (1)

while the lammps documentation shows:

E = Sum(n=1,n) An*cos^(n-1)[phi] Eqn. (2)

Should I assume the equation on lammps means this?

E = A1 + A2*cos[phi] + A3*cos^2[phi] + …

If that is the case, is there any suggestions on how to use Eqn.(1) in lammps? Or are there any equations already in lammps that matches Eqn.(1)? From my search on the documentation, the dihedral_style nharmonic command had the closest similarity to Eqn.(1).

Thanks,

Faraz Saleem

Graduate Student

University of Colorado Colorado Springs