Based on Gel'fand technique and the analysis of phase conventions,a Mathematica programmes worked out for the computation of Su(3) Clebsch Gordan coefficients (CGCs).The results agree with those obtained from the generalized Condon-Shortley Convention.

SCC-DV-Xα computational method of quantum chemistry is used to study the relationship among structure, property and chemical bond of five cement minerals in the system CaO-Al₂O₃, as well as the effect of sodium ion entering into its lattice on property of the mineral. The calculated results show that the order of Ca-O covalent bond strength is C₃A < C₁₂A₇ < CA < CA₂ < CA₆,and the strength of their Ca-O bonds is all less than that of the Al-O bonds, which are consistent with the experimental results of hydration activity of the corresponding cement minerals. After sodium ion entering into the structure of C₃A, Al-O bonds will be strengthened, the hydraulic activation energy is increased, and the density of states is decreased. These are believed as the main reasons for the decrease of hydration activity of doped C₃A.

The correlation among composition, structure, chemical bond and thermoelectric property of boron carbide, phosphide and arsenide is studied with SCF-DV-X_α method, one of calculation methods of molecular orbital in quantum chemistry. The differences between the three materials are studied. As the P-P and As-As chains have no characteristic of double bond, it is difficult for the boron phosphide and arsenide to transfer electrons, though they have the same structure as boron carbide. The C-B-C and C-B-B chains have the characteristic of double bond, so it is easy for the boron carbide to transfer electrons and hop the bipolarons. Therefore, boron phosphide and arsenide have no characteristic of double bond but boron carbide has, which is the main reason that as their thermoelectric property is too bad, boron phosphide and arsenide are not considered as the thermoelectric materials, but boron carbide has the much better thermoelectric property than boron phosphide and arsenide.

Structures, properties and chemical bonds and of ferro aluminates of cement minerals are studied by SCF-X_α-DV method, one of the molecular orbital calculating method in quantum chemistry. The calculated results show that the net charge of Al is higher than that of Fe, the covalent bond of Al-O is weaker than that of Fe-O, and with the increase of Al element content, the net charge of Al becomes higher, the covalent bond of Al O shows weaker, and the energy level of the lowest unoccupied molecular becomes lower, those are just the reason that with the increase of Al element, there is superior hydration activity of ferro aluminates.

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.

The relations among structure property and chemical bond of TiC,TiN and TiO ceramics,as well as Nb doped TiC,are studied with SCF Xα DV,one of the quantum chemistry calculating methods.The calculated results are consistent with the experimental results that the hardness and strength are in the order of TiC > TiN > TiO,and when Nb element added to TiC increases,the vacancies being in short of C atom increase,hardness and resistance of the series samples of (Nb_yTi_1-y)C_x decrease correspondingly.