Silicon oxynitride and oxide glasses are studied with self consistent field discrete variational X_α(SCF-X_α-DV), one of the molecular orbital calculating methods in quantum chemistry. The chemical bonding is studied to discuss the different properties between silicon oxide glass and the glass in which a part of oxygen atoms are substituted by nitrogen atoms. The difference of properties between silicon oxynitride and oxide glasses is not mainly from the difference of stretching force constant, or of ionic bond strength between Si-N and Si-O bonds. The main reason why silicon oxynitride glass possesses better chemical durability and higher elastic modulus than silicon oxide glass lies in the fact that the covalent bond of Si-N is stronger than that of Si-O, and the bending force constant of N-Si N bond is larger than that of the O-Si-O bond.

Te-Se-I glass and adding As,Ge elements to it are studied with Self Consistent Field Diserete Variational X_α (SCF-DV X_α),one of the molecule orbital calculating methods in quantum chemistry.The chemical bonding is studied to discuss the relations between structures and properties with the variations of compositions of the glasses.The calculated results show that the strength of covalent and ionic bonds are both in the order of Ge-Se > As-Se > Te-Se, which is consistent with the experimental result of glass transition temperature(Tg) of the corresponding glasses.The Te-I bond in which I atom is one coordinate is stronger than that in which I atom is two-coordinate,As-I and As As bonds are both stronger than the two types of Te-I bonds.The weak Te-I bonds have been replaced by the stronger As-I and As-As bonds,which is just the reason why with the increace of As element,the structures and properties of Te₂Se_7-x-IAs_x glasses can be changed.