Hypothetical sp3 Allotropes of Silicon, Bct Type, with 3, 5, and 6 Atoms

In this work, we will study basic geometric and electronic structure parameters of hypothetical metaglitter allotropes of silicon, formed by triangular, pentagonal, hexagonal, and octahedral geometries, composed of 6, 10, 12, and 16 atoms. These differ from Si4, which is formed by a square ring interconnected to two others, Si4 anterior and posterior, also by bridges of Si atoms. Its unit cell is composed of 8 atoms. Among its basic electronic characteristics, we will calculate the electron density of all the atoms occupying a unit cell; the electron mobility; the effective mass of free electrons; and the band gap or energy width. We will also study its basic nonlinear optical characteristics, such as first- and third-order susceptibility; and linear and nonlinear refractive index, which characterize these hypothetical allotropes of silicon.