  We develop a boundary element method to calculate Van der Waals interactions
for systems composed of domains of spatially constant dielectric response. We
achieve this by rewriting the interaction energy expression exclusively in
terms of surface integrals of surface operators. We validate this approach in
the Lifshitz case and give numerical results for the interaction of two spheres
as well as the van der Waals self-interaction of a uniaxial ellipsoid. Our
method is simple to implement and is particularly suitable for a full,
non-perturbative numerical evaluation of non-retarded van der Waals
interactions between objects of a completely general shape.
