ABSTRACT
Metals are characterized as having massively degenerate, singly occupied, threedimensional wave functions that formally extend to the edges of the phase. As the example of lithium bonding from small clusters to bulk metal shows,† metallic bonding occurs when the free energy decrease associated with electron delocalization makes delocalized bonding energetically favorable compared to electron pair bonding. This occurs when covalent bonding and delocalized metallic bonding differ by the order of kBT. The phase transition that occurs in the bonding shift is known as a Mott transition [1]. Mott transitions are also known as metal-insulator transitions and are very familiar in condensed matter physics and chemistry [2]. Superconductorinsulator transitions‡ are also documented in the literature [3,4]. On the insulator side of the transition, the bonding in the material is covalent, electron pair bonds, and the material is not a conductor. Mott transitions are known to occur as a function of temperature [1,2], pressure [5], magnetic eld [3], and electric eld [4].
