Theory of Metallic Diamond

Abstract

The fact that compression of Group IV elements and of Groups III-V and II-VI binary compounds forms new denser phases with six near neighbor body-centered tetragonal lattices which are metallic requires theoretical explanation. We think of this new set of metals as being typified by the expected new metallic phase of carbon to be obtained by compression of diamond which we call metallic diamond. It is proposed that this new class of metals of which tin is the only present example under ordinary conditions, and which may include a new metallic form of carbon denser than diamond called metallic diamond, can be understood as a three-dimensional analog of the two-dimensional metal graphite. The excess number of geometrically equivalent nearest neighbors over the four bonds possible from the available electrons and orbitals causes crystal-wide resonance which gives the metallic properties.