The MultiHarmonicDihedral interaction implements a potential that can be expressed as a Fourier expansion of the dihedral angle $\phi$ defined in Dihedral Interactions. The energy is given by

$V(\phi) = K_{0} + \sum_{m=1}^{4} K_{m} \cos(m\phi)$

The parameter file format is a set of rows, in which each row contains a dihedral type index followed by values of K0, ..., K4 for a particular dihedral type. The format is thus

0    K0   K1   K2  K3   K4
1    K0   K1   K2  K3   K4 
....

The first integer in each line is a type index. Different dihedral types must appear in order sequential order 0, 1, 2, etc.