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
Density functional method （B3p86） was used to optimize the structure of the molecule Fe2. The result showed that the ground electronic state for the molecule Fe2 is nonet state instead of septet state, which indicat...Density functional method （B3p86） was used to optimize the structure of the molecule Fe2. The result showed that the ground electronic state for the molecule Fe2 is nonet state instead of septet state, which indicates that there is a spin polarization effect in the molecule Fe2, i.e., in which there are 8 parallel spin electrons.In this case, the number of the unpaired d-orbit electrons is the largest, and these electrons occupy different spatial orbitals so that the energy of the molecule Fe2 is minimized. Meanwhile, the spin pollution was not found because the wave functions of the ground state do not mix with those of the higher energy states. In addition, the Murrell-Sorbie potential functions with the parameters for the ground electronic state and other exited electronic states of the molecule Fe2 were derived. The dissociation energy, equilibrium bond length and the vibration frequency for the ground electronic state of the molecule Fe2 are 3.5522 eV, 0.2137 nm and 292.914 cm^-1, respectively. Its force constants f2, f3 and f4 are 1.4115×1^02 a J/nm^2, -37.1751×103^aJ/nm^3 and 98.7596× 10^4 a J/nm^4, respectively. The other spectroscopic parameters ωexe, Be and αe for the ground electronic state of Fe2 are 0.3522, 0.0345 and 0.4963× 10^-4 cm^-1, respectively.展开更多
The difference of energy and electronic structure of V, Nb, and Ta in different crystalline structures were investigated by different methods in density functional theory （DFT）. Lattice constants, total energies, an...The difference of energy and electronic structure of V, Nb, and Ta in different crystalline structures were investigated by different methods in density functional theory （DFT）. Lattice constants, total energies, and densities of states of these metals were calculated using the plane-wave pseudopotential method in DFT. Results were compared with those of projector augmented wave method, CALPHAD method, and experiments. Total energy and electronic structure analyses showed that valence electrons mostly transferred from s to p or d state, changing obviously with both the crystal structure and the elemental period number from V to Ta and leading to stronger cohesion, higher cohesive energy and more stable lattice of heavier metals.展开更多
To investigate the non-covalent interaction between cyclodextrins （CD） and lithium ion, a stoichiometry of α-CD, β-CD, heptakis（2,6-di-O-methyl）-β-CD （DM-β-CD）, or heptakis（2,3,6-tri-O-methyl）-β-CD （TM-...To investigate the non-covalent interaction between cyclodextrins （CD） and lithium ion, a stoichiometry of α-CD, β-CD, heptakis（2,6-di-O-methyl）-β-CD （DM-β-CD）, or heptakis（2,3,6-tri-O-methyl）-β-CD （TM-β-CD） was mixed with lithium salt, respectively, and then incubated at room temperature for 10 min to reach the equilibrium. In posi- tive mode, the electrospray ionization mass spectrometry （ESI-MS） results demonstrated that lithium ion can conjugate to α-, β-, DM-β- or TM-β-CD and form 1：1 stoichiometric non-covalent complexes. The binding of the complexes was further confirmed by collision- induced dissociation. The dissociation constants Kdl of four complexes （Li＋α-CD, Li＋β- CD, Li＋DM-β-CD, and Li＋TM-β-CD） were determined by mass spectrometric titration. The results showed Kdl were 18.7, 26.7, 33.6, 30.5 μmol/L for the complexes of Li＋ with α-CD, β-CD, DM-β-CD, and TM-β-CD, respectively. Kdl for the Li＋ complexes of/3-CD is smaller than that of DM-β-CD due to its steric effect of the partial substituted -CH3. The Kdl for the Li＋ complexes of DM-β-CD is nearly in agreement with that of TM-β-CD, indicating Li＋ is more likely to locate in the small rim of DM-β-CD＇s hydrophobic cavity. The DFT results showed through electrostatic interaction, one Li＋ can strongly conjugate to four neighboring oxygen atoms. For the （α-CD＋Li）＋ complex, one Li＋ may also situate the small rim of α-CD＇s hydrophobic cavity to form a non-specific host-guest complex.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This work was supported by the National Natural Science Foundation of China （No. 10574096） the Research Fund for the Doctoral Program of High Education （No. 20050610010）.
文摘Density functional method （B3p86） was used to optimize the structure of the molecule Fe2. The result showed that the ground electronic state for the molecule Fe2 is nonet state instead of septet state, which indicates that there is a spin polarization effect in the molecule Fe2, i.e., in which there are 8 parallel spin electrons.In this case, the number of the unpaired d-orbit electrons is the largest, and these electrons occupy different spatial orbitals so that the energy of the molecule Fe2 is minimized. Meanwhile, the spin pollution was not found because the wave functions of the ground state do not mix with those of the higher energy states. In addition, the Murrell-Sorbie potential functions with the parameters for the ground electronic state and other exited electronic states of the molecule Fe2 were derived. The dissociation energy, equilibrium bond length and the vibration frequency for the ground electronic state of the molecule Fe2 are 3.5522 eV, 0.2137 nm and 292.914 cm^-1, respectively. Its force constants f2, f3 and f4 are 1.4115×1^02 a J/nm^2, -37.1751×103^aJ/nm^3 and 98.7596× 10^4 a J/nm^4, respectively. The other spectroscopic parameters ωexe, Be and αe for the ground electronic state of Fe2 are 0.3522, 0.0345 and 0.4963× 10^-4 cm^-1, respectively.
基金ACKNOWLEDGMENTS This work was supported by the Doctoral Discipline Foundation of the Ministry of Education of China （No.20070533118） and the National Natural Science Foundation of China （No.50871124）. The authors acknowledge Dr. Y. Z. Nie for his useful discussion in calculations.
文摘The difference of energy and electronic structure of V, Nb, and Ta in different crystalline structures were investigated by different methods in density functional theory （DFT）. Lattice constants, total energies, and densities of states of these metals were calculated using the plane-wave pseudopotential method in DFT. Results were compared with those of projector augmented wave method, CALPHAD method, and experiments. Total energy and electronic structure analyses showed that valence electrons mostly transferred from s to p or d state, changing obviously with both the crystal structure and the elemental period number from V to Ta and leading to stronger cohesion, higher cohesive energy and more stable lattice of heavier metals.
文摘To investigate the non-covalent interaction between cyclodextrins （CD） and lithium ion, a stoichiometry of α-CD, β-CD, heptakis（2,6-di-O-methyl）-β-CD （DM-β-CD）, or heptakis（2,3,6-tri-O-methyl）-β-CD （TM-β-CD） was mixed with lithium salt, respectively, and then incubated at room temperature for 10 min to reach the equilibrium. In posi- tive mode, the electrospray ionization mass spectrometry （ESI-MS） results demonstrated that lithium ion can conjugate to α-, β-, DM-β- or TM-β-CD and form 1：1 stoichiometric non-covalent complexes. The binding of the complexes was further confirmed by collision- induced dissociation. The dissociation constants Kdl of four complexes （Li＋α-CD, Li＋β- CD, Li＋DM-β-CD, and Li＋TM-β-CD） were determined by mass spectrometric titration. The results showed Kdl were 18.7, 26.7, 33.6, 30.5 μmol/L for the complexes of Li＋ with α-CD, β-CD, DM-β-CD, and TM-β-CD, respectively. Kdl for the Li＋ complexes of/3-CD is smaller than that of DM-β-CD due to its steric effect of the partial substituted -CH3. The Kdl for the Li＋ complexes of DM-β-CD is nearly in agreement with that of TM-β-CD, indicating Li＋ is more likely to locate in the small rim of DM-β-CD＇s hydrophobic cavity. The DFT results showed through electrostatic interaction, one Li＋ can strongly conjugate to four neighboring oxygen atoms. For the （α-CD＋Li）＋ complex, one Li＋ may also situate the small rim of α-CD＇s hydrophobic cavity to form a non-specific host-guest complex.
