The explicit examination of the magnetic states of electrides.

Electrides are a unique class of ionic solids in which the anions are stoichiometrically replaced by electrons localised within the crystal voids. In this work, we present the first density-functional calculations to successfully reproduce the known anti-ferromagnetic behaviour of the organic electrides. Interrogation of the spin densities confirms that the localised, interstitial electrons are indeed the source of magnetism in the electride crystals. Comparison of the relative energies of the ferromagnetic and anti-ferromagnetic states allows prediction of the spin-coupling constants between electrons in neighbouring crystal voids. All major discrepancies between the calculated and experimentally-determined coupling constants reflect obvious deviations from the assumption of a simple, one-dimensional chain of interacting spins. For the electrides where such a model Hamiltonian is valid, the experimental ordering of the coupling constants is reproduced to a remarkable degree of accuracy.