Synthesis, crystal and band structures, and optical properties of a new framework mercury pnictides: [Hg4As2](InBr3.5As0.5) with tridymite topology

▶ Except for the two principal types of frameworks for mercury pnictides reported in the literature, the present compound is a new type of open-framework compounds with tridymite topology. ▶ The optical properties was systematically researched by experimental and computational methods, which provide base for the sequential investigations.