Calculates the 3J coupling constant from the dihedral angle and the electronegativity of the substituents using either the Altona equation or a generalised Karplus equation.
Sweet J can be downloaded here https://www.inmr.net/sweetj.html
Giuseppe Balacco
A Desktop Calculator for the Karplus Equation
J. Chem. Inf. Comput. Sci., 1996, 36 (4), pp 885–887
DOI: 10.1021/ci950227r