Van der Waals forces between cylinders. I. Nonretarded forces between thin isotropic rods and finite size corrections

The free energy of interaction of two long thin dielectric cylinders is evaluated in the nonretarded limit by the method of van Kampen. The result includes all nonadditive many body forces and the effects of an intervening medium. In the limit of dilute systems the result reduces to that obtained by summation of r(-6) pair potentials.

Van der Waals forces between cylinders. II. Retarded interaction between thin isotropic rods

We derive the retarded van der Waals interaction between two long thin parallel dielectric cylinders immersed in a solvent. The result shows that the ultraviolet interactions which may be responsible for the specificity of macromolecular interactions do not operate strongly over distances R >/= 50 A. For greater distances the contribution of these frequencies xi is damped by a factor infinity e(-xiR/c).

Exact Energy of Interaction Between Nonpolar Molecules Represented as Dipoles

A new non-perturbative method is developed for deriving the energy of interaction between molecules represented as polarizable dipoles. The method is applied to obtain the exact energy of interaction for two anisotropic electric dipoles and for three dipoles in the isotropic case. The results of London and of Casimir and Polder are special limiting cases. Deviations of the London energy from the exact result are investigated. A new feature which emerges is that the potential energy becomes repulsive at very small distances of separation.