  Cerium electronic multipoles in trigonal symmetry viewed in magnetic neutron
diffraction are investigated. Analytic expressions for all the magnetic
multipoles, and radial integrals calculated with an established atomic code,
are used to scrutinize a recent claim to have observed an octupole-ice
configuration in a powder sample of pyrochlore Ce2Sn2O7. Three equally
plausible suites of multipoles belonging to uncorrelated cerium ions give
equally satisfactory accounts of the available diffraction pattern. Our
multipoles are suitable for future experiments using Bragg diffraction from a
compound that supports long-range magnetic order.
