A Model of the Electronic Structure of Nanocrystalline Hydrogen

Abstract

Unsuccessful attempts of producing crystalline hydrogen predicted in [1] based on electronic theory do not reduce interest in this hydrogen state in connection with its possible formation in solid-state hydrogen accumulators. The hydrogen density in these materials can approach the value reported in [1]. However, the nonequilibrium state and the presence of defects in the matrix can lead to the formation of nanostructural hydrogen comprising small-sized crystallites with boundaries rather than of a single crystal. The electronic structure of this state has been unknown even in a general form; there is no information on possible mechanisms governing the interaction between nanostructural elements. It is clear only that hydrogen forms a band of weakly hybridized electronic states in hydrides of transition metals [2]. In the zero-order approximation, the elements of hydrogen nanostructure can be represented as cluster fragments of a grain and the intergranular boundary. In this case, the electronic spectra of these fragments can be used to estimate the individual properties of nanostructure elements and (with the use of phenomenological models) the effects of their interaction.