Doped C60 fullerides

Ever since this breakthrough, C60 has been intensively studied and has shown its rich bonding characteristics in various environments, from van der Waals cohesion to ionic and metallic cohesions, and even to the extent of covalent bonding, together also with its rich electronic properties including high transition-temperature (Tc) superconductivity in alkali-doped C60 fullerides. This article reviews the first-principles quantum-mechanical studies of these electronic and bonding properties of C60. 

The most important change to be noted is the appearance of a new gap in the tlu conduction band. The lower and upper subbands can accommodate four and two electrons per C60> respectively. As will be discussed in the next section, there are various fullerides with electrons doped into their conduction bands. The appearance of the new gap in the conduction band indicates therefore that there is a possibility for orientational ordering to induce a metal-insulator transition in electron-doped C60 fullerides. 

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