Potential energy surfaces(PESs), vibrational frequencies, and infrared spectra are calculated for NF_(3)^(+) using ab initio calculations, based on UCCSD(T)/cc-p VTZ combined with vibrational configuration interaction...Potential energy surfaces(PESs), vibrational frequencies, and infrared spectra are calculated for NF_(3)^(+) using ab initio calculations, based on UCCSD(T)/cc-p VTZ combined with vibrational configuration interaction(VCI). Based on an iterative algorithm, the surfaces(SURF) program adds automatic points to the lattice representation of the potential function, the one-dimensional and two-dimensional PESs are calculated after reaching a convergence threshold, finally the smooth image of the potential energy surface is fitted. The PESs accurately account for the interaction between the different modes, with the mode q_(6) symmetrical stretching vibrations having the greatest effect on the potential energy change of the whole system throughout the potential energy surface shift. The anharmonic frequencies are obtained when the VCI matrix is diagonalized. Fundamental frequencies, overtones, and combination bands of NF_(3)^(+) are calculated, which generate the degenerate phenomenon between their frequencies. Finally, the calculated anharmonic frequency is used to plot the infrared spectra.Modal antisymmetric stretching ν_(5) and symmetric stretching ν_(6) exhibit a phenomenon of large-intensity borrowing. This study can provide data to support the characterization in the laboratory.展开更多
Ab initio calculations are performed on the electronic, structural, elastic and optical properties of the cubic per- ovskite KCdF3. Tile Kohn Sham equations are solved by applying the full potential linearized augment...Ab initio calculations are performed on the electronic, structural, elastic and optical properties of the cubic per- ovskite KCdF3. Tile Kohn Sham equations are solved by applying the full potential linearized augmented plane wave （FP-LAPW） method. The exchange correlation effects are included through the local density approximation （LDA ）, generalized gradient approximation （GGA） and modified Becke-Johnson （mBJ） exchange potential The calculated lattice constant is in good agreement with the experimental result. The elastic properties such as elastic constants, anisotropy factor, shear modulus, Young＇s modulus and Poisson＇s ratio are calculated. KCdF3 is ductile and elastically anisotropic. The calculations of the electronic band structure, density of states （DOS） and charge density show that this compound has an indirect energy band gap （M-F） with a mixed ionic and covalent bonding. The contribution of the different bands is analyzed from the total and partial density of states curves. Optical response of the dielectric functions, optical reflectivity, absorption coefficient, real part of optical conductivity, refractive index, extinction coefficient and electron energy loss, are presented for the energy range of O-40eV. The compound KCdF3 can be used for high-frequency optical and optoelectronic devices.展开更多
Employing the ab initio total energy method based on the density functional theory with the generalized gradient approximation, we have systematically investigated the theoretical mechanical properties of copper （Cu...Employing the ab initio total energy method based on the density functional theory with the generalized gradient approximation, we have systematically investigated the theoretical mechanical properties of copper （Cu）. The theoretical tensile strengths are calculated to be 25.3 GPa, 5.9 GPa, and 37.6 GPa for the fcc Cu single crystal in the [001], [110], and [111] directions, respectively. Among the three directions, the [110] direction is the weakest one due to the occurrence of structure transition at the lower strain and the weakest interaction of atoms between the （110） planes, while the [111] direction is the strongest direction because of the strongest interaction of atoms between the （111） planes. In terms of the elastic constants of Cu single crystal, we also estimate some mechanical quantities of polycrystalline Cu, including bulk modulus B, shear modulus G, Young＇s modulus Ep, and Poisson＇s ratio ~.展开更多
B3LYP level density functional theory （DFT） and multiconfiguration self-consistent-field （MCSCF） level ab initio method calculations have been performed on the basis of relativistic effective core potentials to in...B3LYP level density functional theory （DFT） and multiconfiguration self-consistent-field （MCSCF） level ab initio method calculations have been performed on the basis of relativistic effective core potentials to investigate the nature of EuC and EuC2 molecules. The computed results indicate that the ground states of EuC and EuC2 are ^12∑^＋ and SA2, respectively. Dissociation potential energy curves of the low-lying electronic states of EuC have been calculated using the MCSCF method, and the same level calculation on EuC2 indicates that the dissociation energy of EuC2 of ground state compares well with the available experimental data. The bond characteristic is also discussed using Mulliken populations.展开更多
采用量子化学ab initio HF方法，在6-31G（d）基组水平卜，对水杨醛缩乙二胺类双席夫碱及其Ni配合物体系进行几何构型优化．以优化的稳定构型为基础，利用INDO／CI方法计算体系的电子光谱，同时用ZINDO-SOS方法给出该系列分子二阶（βij...采用量子化学ab initio HF方法，在6-31G（d）基组水平卜，对水杨醛缩乙二胺类双席夫碱及其Ni配合物体系进行几何构型优化．以优化的稳定构型为基础，利用INDO／CI方法计算体系的电子光谱，同时用ZINDO-SOS方法给出该系列分子二阶（βijk）和三阶（γijk）非线性光学系数．计算结果表明，共轭性增强有助于增大分子的二阶及三阶非线性光学系数，双席夫碱化合物1的β和γ值分别为35．54×10^-30和-1．20×10^-34 esu，而共轭桥为萘环的化合物4的β和γ值分别为54．22×10^-30和2．00×10^-34 esu，端部引入苯并环的化合物5的β和γ值增加幅度更大．对应的金属Ni（Ⅱ）配合物的β值增加较明显，为配体的1．7～10．8倍，γ值也有不同程度的增加．展开更多
The structure of cage molecule N60 has been calculated by using ab initio method at 6-31G level. The optimized stable geometrical structure of N60 is concave cage with twelve concave-down atoms in the cage. The result...The structure of cage molecule N60 has been calculated by using ab initio method at 6-31G level. The optimized stable geometrical structure of N60 is concave cage with twelve concave-down atoms in the cage. The results of electronic structure calculations can be used for explaining the formation of the concave N60 cage.展开更多
基金Project supported by the National Natural Science Foundation of China (Grant Nos.52002318 and 22103061)。
文摘Potential energy surfaces(PESs), vibrational frequencies, and infrared spectra are calculated for NF_(3)^(+) using ab initio calculations, based on UCCSD(T)/cc-p VTZ combined with vibrational configuration interaction(VCI). Based on an iterative algorithm, the surfaces(SURF) program adds automatic points to the lattice representation of the potential function, the one-dimensional and two-dimensional PESs are calculated after reaching a convergence threshold, finally the smooth image of the potential energy surface is fitted. The PESs accurately account for the interaction between the different modes, with the mode q_(6) symmetrical stretching vibrations having the greatest effect on the potential energy change of the whole system throughout the potential energy surface shift. The anharmonic frequencies are obtained when the VCI matrix is diagonalized. Fundamental frequencies, overtones, and combination bands of NF_(3)^(+) are calculated, which generate the degenerate phenomenon between their frequencies. Finally, the calculated anharmonic frequency is used to plot the infrared spectra.Modal antisymmetric stretching ν_(5) and symmetric stretching ν_(6) exhibit a phenomenon of large-intensity borrowing. This study can provide data to support the characterization in the laboratory.
基金Supported by UGC,New Delhi through UGC-BSR(JRF)fellowships
文摘Ab initio calculations are performed on the electronic, structural, elastic and optical properties of the cubic per- ovskite KCdF3. Tile Kohn Sham equations are solved by applying the full potential linearized augmented plane wave （FP-LAPW） method. The exchange correlation effects are included through the local density approximation （LDA ）, generalized gradient approximation （GGA） and modified Becke-Johnson （mBJ） exchange potential The calculated lattice constant is in good agreement with the experimental result. The elastic properties such as elastic constants, anisotropy factor, shear modulus, Young＇s modulus and Poisson＇s ratio are calculated. KCdF3 is ductile and elastically anisotropic. The calculations of the electronic band structure, density of states （DOS） and charge density show that this compound has an indirect energy band gap （M-F） with a mixed ionic and covalent bonding. The contribution of the different bands is analyzed from the total and partial density of states curves. Optical response of the dielectric functions, optical reflectivity, absorption coefficient, real part of optical conductivity, refractive index, extinction coefficient and electron energy loss, are presented for the energy range of O-40eV. The compound KCdF3 can be used for high-frequency optical and optoelectronic devices.
基金Project supported by the National Natural Science Foundation of China (Grant No. 51101135)
文摘Employing the ab initio total energy method based on the density functional theory with the generalized gradient approximation, we have systematically investigated the theoretical mechanical properties of copper （Cu）. The theoretical tensile strengths are calculated to be 25.3 GPa, 5.9 GPa, and 37.6 GPa for the fcc Cu single crystal in the [001], [110], and [111] directions, respectively. Among the three directions, the [110] direction is the weakest one due to the occurrence of structure transition at the lower strain and the weakest interaction of atoms between the （110） planes, while the [111] direction is the strongest direction because of the strongest interaction of atoms between the （111） planes. In terms of the elastic constants of Cu single crystal, we also estimate some mechanical quantities of polycrystalline Cu, including bulk modulus B, shear modulus G, Young＇s modulus Ep, and Poisson＇s ratio ~.
基金Project supported by the National Natural Science Foundation of China （Grant No 60223003）, Innovation Foundation of Chinese Academy of Sciences and Graduate Innovation Laboratory of Jilin University, China
文摘B3LYP level density functional theory （DFT） and multiconfiguration self-consistent-field （MCSCF） level ab initio method calculations have been performed on the basis of relativistic effective core potentials to investigate the nature of EuC and EuC2 molecules. The computed results indicate that the ground states of EuC and EuC2 are ^12∑^＋ and SA2, respectively. Dissociation potential energy curves of the low-lying electronic states of EuC have been calculated using the MCSCF method, and the same level calculation on EuC2 indicates that the dissociation energy of EuC2 of ground state compares well with the available experimental data. The bond characteristic is also discussed using Mulliken populations.
文摘采用量子化学ab initio HF方法，在6-31G（d）基组水平卜，对水杨醛缩乙二胺类双席夫碱及其Ni配合物体系进行几何构型优化．以优化的稳定构型为基础，利用INDO／CI方法计算体系的电子光谱，同时用ZINDO-SOS方法给出该系列分子二阶（βijk）和三阶（γijk）非线性光学系数．计算结果表明，共轭性增强有助于增大分子的二阶及三阶非线性光学系数，双席夫碱化合物1的β和γ值分别为35．54×10^-30和-1．20×10^-34 esu，而共轭桥为萘环的化合物4的β和γ值分别为54．22×10^-30和2．00×10^-34 esu，端部引入苯并环的化合物5的β和γ值增加幅度更大．对应的金属Ni（Ⅱ）配合物的β值增加较明显，为配体的1．7～10．8倍，γ值也有不同程度的增加．
文摘The structure of cage molecule N60 has been calculated by using ab initio method at 6-31G level. The optimized stable geometrical structure of N60 is concave cage with twelve concave-down atoms in the cage. The results of electronic structure calculations can be used for explaining the formation of the concave N60 cage.
