[lammps-users] custom improper

I am attempting to use an united atom force field with a different form for the improper force. It uses the form

U=k1(phi-phi0)^2+k2(phi-phi0)

I have modified improper_harmonic.cpp but I am unsure if I did this correctly. I have attached the modified cpp file. Thanks

Ben Hanson

improper_PMMA.cpp (7.59 KB)