Theoretical Study On The Molecular Face For Several Five Heterocyclic Compounds And The Process Of FH And Rg Forming Dimer

The molecular face theory is a method to study the size, shape and the foreland electron density of a molecule. Using the molecular face theory, the potential acting on an electron within a molecule and the molecular intrinsic characteristic contours of several heterocyclic compounds including pyrrole, thiophene, pyrazole, thiazole, imidazole and isothiazole were calculated. the changes of the molecular face were explored when every noble gas atom gradually approaches to the H atom in the HF.The geometries of furan, pyrrole, thiophene, isoxazole, pyrazole, isothiazole, oxazole, imidazole and thiazole were optimized with MP2/6-31 l++g(3df,3pd) and the first ionization energy of these molecules were calculated of the ground stste with MP2/6-31g, respectively. The coefficients of each atom in the heterocyclic compounds on the HOMO were calculated, and the figures of the HOMO were given. By using CISD/3-21+g (d, p) in the ab initio MELD package and our in-house molecular face program, the molecular faces were depicted. Meanwhile, the potential acting on an electron within a molecule, PAEM, was systematically investigated for these molecules. Moreover, the relationship between the potential, Dpb, in chemical bond region, and the strength of chemical bond was explored. It can be shown that certain relationship exists between the potential of the ring center and the polarizability of the molecule, which can be used to characterize the deformation of molecule. The molecular intrinsic characteristic contours and the even electron density on the molecular surface were calculated. The relationship between the even electron density on the molecular interface and the aromaticity of five heterocyclic compounds were analyzed.The study of the molecular face of FH---Rg(Rg= He, Ne, Ar, Kr). The geometries of the FH---Rg were optimized with MP2/6-311++g(2d,2p) when the distance between the H atom of HF molecule and the noble gas atom varies from 8 A to 2 A. The first ionization energies of these dimers of the ground state were calculated and the trend was provided. The coefficients of each atom in each dimer on the HOMO were calculated with MP2/STO-3G, and the figures of the HOMO were given. The trend of the first ionization energies were analyzed combining the coefficients. Using the CISD method of the ab initio MELD package combined with our in-house program, the molecular faces have been displayed and explored for FH---Rg (Rg=He, Ne, Ar, Kr) dimers. The changes of the molecular faces were given when every noble gas atom gradually approaches to the H atom in the HF. The polarizability of the dimer gradually increases, the deformation of the atom in the dimer increases, when the distance beween the noble gas atom and the H atom changes from 8.0 A to 2.0 A. From the character provided by the foreland electron density, we can find out the difference of the interaction between the noble gas and the HF. The character is also a vivid implement to distinguish the interaction between the covalent and the non-covalent.