The complete harmonic vibrational force field of dimethylnitramine has been calculated at the Hartree-Fock level using 4-21G basis set.The harmonic force field was then scaled with scale factors previously derived fro...The complete harmonic vibrational force field of dimethylnitramine has been calculated at the Hartree-Fock level using 4-21G basis set.The harmonic force field was then scaled with scale factors previously derived from N-methylnitramine,and the vibrational spectrum of dimethylnitramine was computed.This apriori prediction,made with no reference to observations on dimethylnitramine, agrees with the experimental IR spectrum in gas phase with a mean deviation of 8.4 cm^(-1).Some of the scale factors were reoptimized by fitting of the computed force field to experimental data.The new set of scale factors reduced the mean deviation to 4.5 cm^(-1),and was used to predict the vibrational spectrum of deuterated form of dimethylnitramine(-6D).Dipole moment derivatives were also cal- culated and used to predict infrared intensities which are comparable with experimental values.展开更多
The geometries of 3 X 2(1H) pyridones(X=NO 2, NH 2, COOH) and their tautomers in the gas phase and DMSO solution(SCRF) have been obtained at HF/6 31G ** and MP2/6 31G ** levels. The influences of intramolecular hydrog...The geometries of 3 X 2(1H) pyridones(X=NO 2, NH 2, COOH) and their tautomers in the gas phase and DMSO solution(SCRF) have been obtained at HF/6 31G ** and MP2/6 31G ** levels. The influences of intramolecular hydrogen bond on the tautomeric equilibrium have also been investigated. In the gas phase, the calculated results show that the enol form is more stable than the keto form for 3 NO 2 2(1H) pyridone, and the ketoenol equilibrium shift right due to the formation of intramolecular hydrogen bond between 3 nitro and 2 hydroxyl group, while for the amino and carboxyl derivatives, the keto forms are favored over the enol forms because of the stronger intermolecular hydrogen bonds in keto tautomers. However, owing to the polarization effects of solvent, it can be predicted that the keto tautomers are dominant for all of the title compounds in DMSO solution, which are in good agreement with the experimental results.展开更多
Molecular dynamics （MD） computer simulation techniques, as a powerful tool commonly utilized by the liquid crystal display （LCD） community, usually are employed for computing the equilibrium and transport properti...Molecular dynamics （MD） computer simulation techniques, as a powerful tool commonly utilized by the liquid crystal display （LCD） community, usually are employed for computing the equilibrium and transport properties of a classical many body system, since they are very similar to real experiments in many respects. In this paper we pre- sent molecular dynamics computer simulation results taken for a mixture of the two different kinds of nematic liq- uid crystals （LCs）. We calculated rotational viscosity from Brownian behavior with friction of the mean director of the mixture comprising pentylcyanobiphenol （5CB） and decylcyanobiphenol （10CB） by using molecular dynamics computer simulation, where intermolecular potential parameter is Generalized AMBER force field （GAFF）. Our computed results show a good agreement with the experimental results.展开更多
Using the recently developed method we calculated the crystal field parameters m yttrium anct lutetium aluminum garnets doped with seven trivalent Krarners rare-earth ions. We then inserted calculated parameters into ...Using the recently developed method we calculated the crystal field parameters m yttrium anct lutetium aluminum garnets doped with seven trivalent Krarners rare-earth ions. We then inserted calculated parameters into the atomic-like Hamiltonian taking into account the electron-electron, spin-orbit and Zeeman interactions and determined the multiplet splitting by the crystal field as well as magnetic tensors. We compared calculated results with available experimental data. Very good agreement with the spectroscopic data and qualitative agreement with experimental tensors was found.展开更多
The Buckingham expansion is important for understanding molecular multipoles and(hyper)polarizabilities.In this study,we give a complete derivation of the Buckingham expansion in the traced form using successive Taylo...The Buckingham expansion is important for understanding molecular multipoles and(hyper)polarizabilities.In this study,we give a complete derivation of the Buckingham expansion in the traced form using successive Taylor series.Based on the derivation results,a general Buckingham expansion in the traced form is proposed,from which highly accurate numerical calculations using the finite field method can be achieved.The transformations from the traced multipoles and multipole-multipole polarizabilities to the corresponding traceless counterparts are realized with an auxiliary traced electric field gradient.The applications of thefinite field method in this study show good agreements with previous theoretical calculations and experimental measurements.展开更多
基金Project supported by the National Natural Science Foundation of China.
文摘The complete harmonic vibrational force field of dimethylnitramine has been calculated at the Hartree-Fock level using 4-21G basis set.The harmonic force field was then scaled with scale factors previously derived from N-methylnitramine,and the vibrational spectrum of dimethylnitramine was computed.This apriori prediction,made with no reference to observations on dimethylnitramine, agrees with the experimental IR spectrum in gas phase with a mean deviation of 8.4 cm^(-1).Some of the scale factors were reoptimized by fitting of the computed force field to experimental data.The new set of scale factors reduced the mean deviation to 4.5 cm^(-1),and was used to predict the vibrational spectrum of deuterated form of dimethylnitramine(-6D).Dipole moment derivatives were also cal- culated and used to predict infrared intensities which are comparable with experimental values.
文摘The geometries of 3 X 2(1H) pyridones(X=NO 2, NH 2, COOH) and their tautomers in the gas phase and DMSO solution(SCRF) have been obtained at HF/6 31G ** and MP2/6 31G ** levels. The influences of intramolecular hydrogen bond on the tautomeric equilibrium have also been investigated. In the gas phase, the calculated results show that the enol form is more stable than the keto form for 3 NO 2 2(1H) pyridone, and the ketoenol equilibrium shift right due to the formation of intramolecular hydrogen bond between 3 nitro and 2 hydroxyl group, while for the amino and carboxyl derivatives, the keto forms are favored over the enol forms because of the stronger intermolecular hydrogen bonds in keto tautomers. However, owing to the polarization effects of solvent, it can be predicted that the keto tautomers are dominant for all of the title compounds in DMSO solution, which are in good agreement with the experimental results.
文摘Molecular dynamics （MD） computer simulation techniques, as a powerful tool commonly utilized by the liquid crystal display （LCD） community, usually are employed for computing the equilibrium and transport properties of a classical many body system, since they are very similar to real experiments in many respects. In this paper we pre- sent molecular dynamics computer simulation results taken for a mixture of the two different kinds of nematic liq- uid crystals （LCs）. We calculated rotational viscosity from Brownian behavior with friction of the mean director of the mixture comprising pentylcyanobiphenol （5CB） and decylcyanobiphenol （10CB） by using molecular dynamics computer simulation, where intermolecular potential parameter is Generalized AMBER force field （GAFF）. Our computed results show a good agreement with the experimental results.
基金supported by the Czech Science Foundation(13-09876S)
文摘Using the recently developed method we calculated the crystal field parameters m yttrium anct lutetium aluminum garnets doped with seven trivalent Krarners rare-earth ions. We then inserted calculated parameters into the atomic-like Hamiltonian taking into account the electron-electron, spin-orbit and Zeeman interactions and determined the multiplet splitting by the crystal field as well as magnetic tensors. We compared calculated results with available experimental data. Very good agreement with the spectroscopic data and qualitative agreement with experimental tensors was found.
基金the National Natural Science Foundation of China(Grant Nos.21573112 and 21421001)。
文摘The Buckingham expansion is important for understanding molecular multipoles and(hyper)polarizabilities.In this study,we give a complete derivation of the Buckingham expansion in the traced form using successive Taylor series.Based on the derivation results,a general Buckingham expansion in the traced form is proposed,from which highly accurate numerical calculations using the finite field method can be achieved.The transformations from the traced multipoles and multipole-multipole polarizabilities to the corresponding traceless counterparts are realized with an auxiliary traced electric field gradient.The applications of thefinite field method in this study show good agreements with previous theoretical calculations and experimental measurements.
