Retarded van der Waals Potential between Pairs of Spinless Atoms

The retarded van der Waals potential between pairs of spinless atoms, H-H, H-He, He-He, Ne-Ne, Ne-Ar, and Ar-Ar, was computed with covariant formulas of Feinberg and Sucher. Electric and magnetic effects were treated on equal footing. For hydrogen, which posses-a large magnetic polarizability, magnetic effects dominate for large distance of separation, and for small distances, an additional contribution to the London constant for a pair of hydrogen atoms from the magnetic effects is found to be $0.0155{{\alpha }_a}^5$, about 0.24% of the currently accepted value.