Potential energy scan for uranium oxide （UO） was performed by ab initio configuration inter- action （CI） method and density functional theory methods at the PBE1 and the B3LYP levels in combination with the （ECPS...Potential energy scan for uranium oxide （UO） was performed by ab initio configuration inter- action （CI） method and density functional theory methods at the PBE1 and the B3LYP levels in combination with the （ECPSOMWB_AVQZ＋2f） basis set for uranium and 6-311＋G＊ for oxygen. The dissociation energies of UO, after being corrected for the zero-point vibrational energy, are 2.38, 3.76, and 3.31 eV at the CI, PBE1, and BaLYP levels, respectively. The calculated energy was fitted to potential functions of Morse, Lennard-Jones, and Rydberg. Only the Morse function is eligible for the potential. The anharmonieity constant is 0.00425. The anharmonic frequency is 540.95 em-1 deduced from the PBE1 results. Thermodynamic properties of entropy and heat capacity at 298.2-1500 K were calculated using DFT-UPBE1 results and Morse parameters. The relationship between entropy and temperature was established.展开更多
Geometric structures of 135 polychlorinated acenaphthylene （PCAC） molecules were optimized using density functional theory （DFT） at the B3LYP/6-311G^＊＊ level and some thermodynamic properties of them in the idea...Geometric structures of 135 polychlorinated acenaphthylene （PCAC） molecules were optimized using density functional theory （DFT） at the B3LYP/6-311G^＊＊ level and some thermodynamic properties of them in the ideal gas state were calculated. The relations of these thermodynamic properties with the number and position of chlorine atoms were also explored, from which the relative stability of PCAC congeners was theoretically proposed according to the magnitude of the relative standard Gibbs free energy of formation （△r,fGθ）. The results show that all PCAC isomers have planar geometric configuration. There exists intramolecular Cl···Cl weak interaction in some PCAC molecules. The change of △fHθ and fGθ of most stable PCAC isomers with increasing the number of chlorine atoms is different from that in the least stable PCAC congeners. The values of fHθ and fGθ for PCAC isomers with the same number of chlorine atoms show a strong dependence on the position of chlorine atoms and the relative stability of PCAC congeners has close relation with the intramolecular Cl···Cl nuclear repulsive interaction.展开更多
Ab initio self-consistent field (SCF) and M0Der-Plesset correlationcorrection methods employing 6-31G^(**) basis set have been applied to the optimizations ofnitroamine dimers. The binding energies have been corrected...Ab initio self-consistent field (SCF) and M0Der-Plesset correlationcorrection methods employing 6-31G^(**) basis set have been applied to the optimizations ofnitroamine dimers. The binding energies have been corrected for the basis set superposition error(BSSE) and the zero-point energy. Three optimized dimers have been obtained. The BSSE correctedbinding energy of the most stable dimer is predicted to be - 31.85 kJ/mol at the MP4/6-31G^(**)//MP2/6-31G^(**) level. The energy barriers of the Walden conversion for - NH_2 group are 19.7kJ/mol and 18.3 kJ/mol for monomer and the most stable dimer, respectively. The molecularinteraction makes the internal rotation around N_1 - N_2 even more difficult. The thermodynamicproperties of nitroamine and its dimers at different temperatures have been calculated on the basisof vibrational analyses. The change of the Gibbs free energy for the aggregation from monomer to themost stable dimer at standard pressure and 298.2 K is predicted to be 14.05 kJ/mol.展开更多
文摘Potential energy scan for uranium oxide （UO） was performed by ab initio configuration inter- action （CI） method and density functional theory methods at the PBE1 and the B3LYP levels in combination with the （ECPSOMWB_AVQZ＋2f） basis set for uranium and 6-311＋G＊ for oxygen. The dissociation energies of UO, after being corrected for the zero-point vibrational energy, are 2.38, 3.76, and 3.31 eV at the CI, PBE1, and BaLYP levels, respectively. The calculated energy was fitted to potential functions of Morse, Lennard-Jones, and Rydberg. Only the Morse function is eligible for the potential. The anharmonieity constant is 0.00425. The anharmonic frequency is 540.95 em-1 deduced from the PBE1 results. Thermodynamic properties of entropy and heat capacity at 298.2-1500 K were calculated using DFT-UPBE1 results and Morse parameters. The relationship between entropy and temperature was established.
基金supported by the Natural Science Research Program of Henan Provincial Department of Education (No. 2009A150022)the Young Talented Teacher Foundation of Xinyang Normal University
文摘Geometric structures of 135 polychlorinated acenaphthylene （PCAC） molecules were optimized using density functional theory （DFT） at the B3LYP/6-311G^＊＊ level and some thermodynamic properties of them in the ideal gas state were calculated. The relations of these thermodynamic properties with the number and position of chlorine atoms were also explored, from which the relative stability of PCAC congeners was theoretically proposed according to the magnitude of the relative standard Gibbs free energy of formation （△r,fGθ）. The results show that all PCAC isomers have planar geometric configuration. There exists intramolecular Cl···Cl weak interaction in some PCAC molecules. The change of △fHθ and fGθ of most stable PCAC isomers with increasing the number of chlorine atoms is different from that in the least stable PCAC congeners. The values of fHθ and fGθ for PCAC isomers with the same number of chlorine atoms show a strong dependence on the position of chlorine atoms and the relative stability of PCAC congeners has close relation with the intramolecular Cl···Cl nuclear repulsive interaction.
文摘Ab initio self-consistent field (SCF) and M0Der-Plesset correlationcorrection methods employing 6-31G^(**) basis set have been applied to the optimizations ofnitroamine dimers. The binding energies have been corrected for the basis set superposition error(BSSE) and the zero-point energy. Three optimized dimers have been obtained. The BSSE correctedbinding energy of the most stable dimer is predicted to be - 31.85 kJ/mol at the MP4/6-31G^(**)//MP2/6-31G^(**) level. The energy barriers of the Walden conversion for - NH_2 group are 19.7kJ/mol and 18.3 kJ/mol for monomer and the most stable dimer, respectively. The molecularinteraction makes the internal rotation around N_1 - N_2 even more difficult. The thermodynamicproperties of nitroamine and its dimers at different temperatures have been calculated on the basisof vibrational analyses. The change of the Gibbs free energy for the aggregation from monomer to themost stable dimer at standard pressure and 298.2 K is predicted to be 14.05 kJ/mol.
