Carbon-/boron-/nitrogen-substituted germaneness

In this chapter, boron-, carbon- and nitrogen-substituted germanene systems exhibit the diverse orbital hybridizations and spin configurations, as thoroughly examined from the first-principles simulations for the highly non-uniform chemical bonds, the atom- & spin-dominated band structures within the specific energy ranges, the spatial charge/spin densities & their variations after the chemical substitutions, and the atom-, orbital- & spin-projected density of states. The featured quasiparticle properties cover the position-dependent chemical bonds under the various substitution cases, the diversified energy spectra & wave functions, the diversified orbital hybridizations, and various van Hove singularities due to different critical points. Through the detailed analyses of all relevant quantities, the specific orbital hybridizations are the dominant π & σ bondings and the minor sp3 ones in a pristine monolayer germanene, the [4s, 4px, 4py,4pz]-[4s, 4px, 4py,4pz] and [4s, 4px, 4py,4pz]-[2s, 2px, 2py,2pz] mixings, respectively, in Ge–Ge, Ge–B/Ge–C/Ge–N and B–B/C–C/N–N bonds of buckled binary compounds, as well as, the almost perpendicular π & σ bondings for non-buckled systems. Also noticed that the hopping integrals and the one-site Coulomb potentials very differ from one another among these complex orbital mixings under the distinct atomic configurations.