Title: Casimir-Polder size consistency -- a constraint violated by some dispersion theories,
Abstract: A key goal in quantum chemistry methods, whether ab initio or otherwise, is
to achieve size consistency. In this manuscript we formulate the related idea
of "Casimir-Polder size consistency" that manifests in long-range dispersion
energetics. We show that local approximations in time-dependent density
functional theory dispersion energy calculations violate the consistency
condition because of incorrect treatment of highly non-local "xc kernel"
physics, by up to 10% in our tests on closed-shell atoms.