Hi,

I wish to apply an harmonic functional form with a summation of 3 possible terms to a dihedral angle. i.e., E_torsion = SUM_n=1,3 { K(n) * [ 1 + d*cos(n*Phi ) ] } --(1). I know I should use multi/harmonic dihedral style, but this style uses the potential E_torsion = SUM_n=1,5 [ A(n)*cos^(n-1) {Phi}] --(2), as seen in the documentation. Since (2) has a linear term and 4 cosine terms with power 1 to 4, whereas (1) has only a linear term with 3 coefficients (K1,K2,K3) and 3 cosine power 1 terms with different coefficients, I would like to ask how (1) can be related to (2)?

Thank you.

Christopher