Electronic structure and bonding of β-rhombohedral boron using cluster fragment approach

Abstract

Theoretical studies using density functional theory are carried out to understand the electronic structure and bonding and electronic properties of elemental β-rhombohedral boron. The calculated band structure of ideal β-rhombohedral boron (B₁₀₅) shows valence electron deficiency and depicts metallic behavior. This is in contrast to the experimental result that it is a semiconductor. To understand this ambiguity we discuss the electronic structure and bonding of this allotrope with cluster fragment approach using our recently proposed mno rule. This helps us to comprehend in greater detail the structure of B₁₀₅ and materials which are closely related to β-rhombohedral boron. The molecular structures B₁₂H₁₂^-2, B₂₈H₂₁⁺¹, BeB₂₇H₂₁, LiB₂₇H₂₁^-1, CB₂₇H₂₁₊₂, B₅₇H₃₆⁺³, Be₃B₅₄H₃₆, and Li₂CB₅₄H₃₆, and corresponding solids Li₈Be₃B₁₀₂ and Li₁₀CB₁₀₂ are arrived at using these ideas and studied using first principles density functional theory calculations.