The Theoretical Study On Diatomic Molecules In Terms Of Molecular Face Theory

We have studied the properties of AB model diatomic molecules by usingCISD/6-311G*and CISD/6-31G*, when A stands for F, H, Li, Be, B, C, N, O atoms and Bacts Li, Be, B, C, N, O, F, Cl, Br, I atoms.We optimize all molecules by the selected method and get the structure of molecules.The first ionization energies and distances between the atoms have been calculated. Theparameters are equal to theoretical values, which prove that the method and basis set arereasonable. By using CISD/6-311G*in the ab initio MELD package and our in-housemolecular face program, the potential acting on an electron within a molecule, the iso-valuegraph of the PAEM and molecular faces were depicted. The size of the PAEM associated withits atomic number.According to the molecular face theory, the bond length and force constantare associated with PAEM, a new physical quantity Dpbis established and its is can measurethe strength of chemical bond. To discuss the relationship between the electron densitydistribution and the chemical properties of atoms, the atoms who have stronger ability toattract electron, gathered more electrons around the nucleus, and the volume is greater. Byusing VMF, we get the molecular surface area and volume. C, N, O, F, the nuclear chargenumber is incremental，isolated atomic radius is diminishing, the (S/a.u.^2) and (V/a.u.^3)of the diatomic molecules which form with the same atoms are diminishing. The same maingroup elements, F、Cl、Br、I, the nuclear charge number is incremental, isolated atomic radiusis incremental, the S and V of the diatomic molecules which form with the same atoms areincremental. We have calculated the parameters R(R/a.u.) of molecular face contour and theboundary electronic density ED(ED/10-3a.u.)of diatomic molecules. One atom is non-metaland other atom is metal in the diatomic molecule, The metal atoms loses partial electrons,non-metal atom gets partial electronics, and form a stable structure. Therefore, in AB modeldiatomic molecules, when B is metal atom, contour characteristic radius are more than isolateatomic radius, it is expansion, when B is non-metal atom, contour characteristic radius areless than isolate atomic radius, it is contraction.