Dear All users

I should a force field for CaCO3 that includes these terms for bonded interaction:

Harmonic bond stretch term , harmonic cosine angle bending term , inversion term is of the

umbrella type , bond-angle and bond-bond cross-terms:

The last term is :

D(R1 - R1,0)(cos θ - cos θ0) + E(R2 - R2,0)(cos θ - cos θ0) + KR1R2(R1 - R1,0)(R2 - R2,0)

I can’t find this cross term in the manual, Is it possible to use this cross term in Lammps input?