Dear sir,

I am facing a problem regarding the dihedral style. I want to use multi harmonic dihedral style for my alkane simulation. But

the form of multi harmonic dihedral in lammps has five coefficients. The potential models available in literature for alkanes

have six or nine or four coefficients. So is it possible to modify few of the lammps subroutines so that the multi harmonic

dihedral can accomodate six coefficients instead of existing five coefficients? If possible which subroutines should I modify.

I have given below the details that I want to do.

lammps multi harmonic dihedral form is

V = sum_i={1,5}(A_i*cos^(i-1)(phi))

I want to add one more term to this function that is the sumation going from 1 to 6 instead of 1 to 5.

Any suggestions is highly appreciated.

kind regards

Srinivas