Quantum-mechanical calculations of atoms charge state in Cd 2 P 3 Cl(Br,I) single crystals

The cluster models of the ideal and defect single crystals of the Cd 2 P 3 Г family (Г = Cl, Br, І) are constructed. Basing of the extended Huckel method a distribution of the electron population on the atoms and changes of the charge state of the phosphorus atoms at replacement of the chalkogen in these compounds are theoretically studied. A possibility of formation of the phosphorus vacancies and their positions in the crystal lattice is considered from energy point of view. It was revealed that the calculations of the both ideal and defect crystals do not give a positive valence of the phosphorus atoms and do not confirm two-anion - two-cation model of the charge states in these compounds. The most consistent with the calculations is a formula Cd 2 2+ P 3 1- Г 1- .