First-Principles Study of the Electronic Structure of Na_xH_yC₆₀

Abstract

We investigated theoretically the electronic structure of a newC₆₀ based superconductor, Na_xH_yC₆₀ where x -- 3.6and y -- 1, to provide criteria that enable one to identify whichof two possible phases, Na₃HC₆₀ and Na₄HC₆₀, isimportant to the superconductivity. Studying these two phases byusing the first-principles calculations, we found remarkabledifferences in the electronic structures between them, especially inthe partial densities of states and the nuclear-quadrupoleinteraction of ²³Na. We propose that these quantities can workas the criteria for the identification.