Vicinal proton-phosphorus coupling constants

This program calculates 3JHP values according to the modified Karplus equation

J = A cos2(d) - B cos(d) + C,

(where A = 15.3, B = 6.1, C = 1.6)*
Dihedral angle => 3JHH

* the coefficients are taken from Lankhorst, P. P.; Haasnoot, C. A. G.; Erkelens, C.; Altona, C. J .Biomol. Struct. Dyn. 1984, I , 1387.