Electronic energy gap, F-x polyhedra

• Ca-F
• C-F
• Ba-Cu-F-O-Y
• F-H-N
• F-H-K
• values of electronic energy gap
• energy gap for direct transition
• energy gap for indirect transition
• thermal energy gap
• charge-transfer energy
• halogen
• fluoride
• non-disordered
• transitional
• monoclinic
• orthorhombic
• cubic
• tetragonal
• trigonal