利用等键反应,以密度泛函方法对24种硝酸酯化合物的生成焓进行了计算,并将其中5种化合物的计算结果与实验值作了对比。计算中采用的基组为6-31G**和6-311G**。计算结果表明:B3PW91/6-31G**方法可以得到可信的生成焓,平均绝对偏差为4.5 k...利用等键反应,以密度泛函方法对24种硝酸酯化合物的生成焓进行了计算,并将其中5种化合物的计算结果与实验值作了对比。计算中采用的基组为6-31G**和6-311G**。计算结果表明:B3PW91/6-31G**方法可以得到可信的生成焓,平均绝对偏差为4.5 k J/mol。进一步利用B3PW91/6-31G**方法计算了其他19种硝酸酯化合物的生成焓。计算结果表明:对于直链硝酸酯化合物,当亚甲基基团数目增加时,计算得到的生成焓减少,放出的热量更多。展开更多
Optimized geometry and harmonic vibrational frequency of 2-dicyanovinyl-5-（4- ethoxyphenyl）thiophene （C16Hj2N2OS） are calculated at the HF/6-31＋＋G（d,p） and B3LYP/6- 311 ＋＋G（d,p） levels. Mulliken charges in...Optimized geometry and harmonic vibrational frequency of 2-dicyanovinyl-5-（4- ethoxyphenyl）thiophene （C16Hj2N2OS） are calculated at the HF/6-31＋＋G（d,p） and B3LYP/6- 311 ＋＋G（d,p） levels. Mulliken charges in the ground state are also calculated. The research shows the presence of intermolecular interaction in the title compound. The scaled harmonic vibrational frequencies have been compared with experimental FT-IR spectra. A detailed interpretation of the infrared spectra of the title compound is reported. The theoretical spectrograms for IR spectra of the title compound have been constructed, The isotropic chemical shift computed by 13C and 1H NMR analyses also shows good agreement with the experimental observations.展开更多
Density functional method was used to investigate the IR spectrum, heat of forma- tion and thermal stability of a new energetic material bis（2,2-dinitropropyl） formal （BDNPF）. The detonation velocity and pressure ...Density functional method was used to investigate the IR spectrum, heat of forma- tion and thermal stability of a new energetic material bis（2,2-dinitropropyl） formal （BDNPF）. The detonation velocity and pressure were evaluated by using the Kamlet-Jacobs equations based on the theoretical density and heat of formation. The bond dissociation energies for the weakest bonds were analyzed to investigate the thermal stability of the title compound. The results show that the C（I ）-N（I ） bond is predicted to be the trigger bond during pyrolysis. The crystal structure obtained by molecular mechanics belongs to the P21 space group, with the lattice parameters to be Z = 2, a = 11.5254, b = 6.2168, c = 9.5000 A andp= 1.66 g/cm3.展开更多
The structural and electronic properties of the solid 5,7-dinitrobenzo-1,2,3,4-tetrazine-1,3-dioxide（DNBTDO） under the hydrostatic pressure of 0~100 GPa were investigated using density functional theory method. The ...The structural and electronic properties of the solid 5,7-dinitrobenzo-1,2,3,4-tetrazine-1,3-dioxide（DNBTDO） under the hydrostatic pressure of 0~100 GPa were investigated using density functional theory method. The predicted crystal structure with the LDA/CA-PZ functional agrees well with the experimental data at the ambient pressure. The structural results show that the b axis is the most compressible, whereas the a and c axes both have slight variation with pressure. The band gap generally decreases with the increasing pressure, which shows that the DNBTDO molecular crystal undergoes an electronic phase transition from semiconductor to metallic system. Through the analysis of band gap, the title compound is most sensitive at 70 GPa. The density of states analysis indicates that the strong peaks split into some small peaks and become wider under compression, which shows the increase of charge overlap and delocalization among the bonded atoms in the system.展开更多
Density functional calculations were used to investigate the structural,electronic,optical and thermal properties of Cr_4AlB_6.The optimized lattice constants and atomic positions accord well with the experimental dat...Density functional calculations were used to investigate the structural,electronic,optical and thermal properties of Cr_4AlB_6.The optimized lattice constants and atomic positions accord well with the experimental data.The analysis of band structure and density of states confirms the metallic nature of Cr_4AlB_6.The static dielectric constant e1（0） is about 128.0,and the maximum optical conductivity occurs at about 8.12 eV.In the photon energy range from 7.87 to 23.48 e V,Cr_4AlB_6 presents a metal reflective property.The plasma resonance frequency wp of Cr_4AlB_6 is at the photon energy of 23.85 eV,and Cr_4AlB_6 will be transparent and change from metallic to dielectric response if the incident light has frequency greater than the plasma frequency of Cr_4AlB_6.Thermodynamic properties including the primitive cell volume and thermal expansion,the bulk modulus and heat capacity Cv were further investigated with the increasing temperature and pressure by using the quasi-harmonic Debye model.展开更多
Using the time-dependent multilevel approach, we have calculated the coherent population transfer between the quantum states of potassium atom by a single frequency-chirped laser pulse. The result shows that a pair of...Using the time-dependent multilevel approach, we have calculated the coherent population transfer between the quantum states of potassium atom by a single frequency-chirped laser pulse. The result shows that a pair of sequential ＇broadband＇ frequency-chirped laser pulses can efficiently transfer population from the initial state of the ladder system to the target state. It is also found that the population can be efficiently transferred to a target state and trapped there by using an ＇intuitive＇ or a ＇counterintuitive＇ frequency sweep laser pulse in the case of ＇narrowband＇ frequency-chirped laser pulse. Our research shows that the complete population transfer is related to the pulse duration, chirp rate, and amplitude of the laser pulse.展开更多
文摘利用等键反应,以密度泛函方法对24种硝酸酯化合物的生成焓进行了计算,并将其中5种化合物的计算结果与实验值作了对比。计算中采用的基组为6-31G**和6-311G**。计算结果表明:B3PW91/6-31G**方法可以得到可信的生成焓,平均绝对偏差为4.5 k J/mol。进一步利用B3PW91/6-31G**方法计算了其他19种硝酸酯化合物的生成焓。计算结果表明:对于直链硝酸酯化合物,当亚甲基基团数目增加时,计算得到的生成焓减少,放出的热量更多。
基金Supported by the National Natural Science Foundation of China (No. 10774039)the key project of Henan Educational Committee (No. 12A140004)Henan University of Science and Technology for Young Scholars (No. 2009QN0032)
文摘Optimized geometry and harmonic vibrational frequency of 2-dicyanovinyl-5-（4- ethoxyphenyl）thiophene （C16Hj2N2OS） are calculated at the HF/6-31＋＋G（d,p） and B3LYP/6- 311 ＋＋G（d,p） levels. Mulliken charges in the ground state are also calculated. The research shows the presence of intermolecular interaction in the title compound. The scaled harmonic vibrational frequencies have been compared with experimental FT-IR spectra. A detailed interpretation of the infrared spectra of the title compound is reported. The theoretical spectrograms for IR spectra of the title compound have been constructed, The isotropic chemical shift computed by 13C and 1H NMR analyses also shows good agreement with the experimental observations.
基金supported by the National Natural Science Foundation of China(No.U1304111)China Postdoctoral Science Foundation(No.2013M531361)Jiangsu Planned Projects for Postdoctoral Research Funds(No.1201015B)
文摘Density functional method was used to investigate the IR spectrum, heat of forma- tion and thermal stability of a new energetic material bis（2,2-dinitropropyl） formal （BDNPF）. The detonation velocity and pressure were evaluated by using the Kamlet-Jacobs equations based on the theoretical density and heat of formation. The bond dissociation energies for the weakest bonds were analyzed to investigate the thermal stability of the title compound. The results show that the C（I ）-N（I ） bond is predicted to be the trigger bond during pyrolysis. The crystal structure obtained by molecular mechanics belongs to the P21 space group, with the lattice parameters to be Z = 2, a = 11.5254, b = 6.2168, c = 9.5000 A andp= 1.66 g/cm3.
基金supported by the National Natural Science Foundation of China(No.U1304111)Program for Science&Technology Innovation Talents in Universities of Henan Province(No.14HASTIT039)the Innovation Team of Henan University of Science and Technology(2015XTD001)
文摘The structural and electronic properties of the solid 5,7-dinitrobenzo-1,2,3,4-tetrazine-1,3-dioxide（DNBTDO） under the hydrostatic pressure of 0~100 GPa were investigated using density functional theory method. The predicted crystal structure with the LDA/CA-PZ functional agrees well with the experimental data at the ambient pressure. The structural results show that the b axis is the most compressible, whereas the a and c axes both have slight variation with pressure. The band gap generally decreases with the increasing pressure, which shows that the DNBTDO molecular crystal undergoes an electronic phase transition from semiconductor to metallic system. Through the analysis of band gap, the title compound is most sensitive at 70 GPa. The density of states analysis indicates that the strong peaks split into some small peaks and become wider under compression, which shows the increase of charge overlap and delocalization among the bonded atoms in the system.
基金supported by the National Natural Science Foundation of China(No.U1304111)Program for Science&Technology Innovation Talents in Universities of Henan Province(No.14HASTIT039)the Innovation Team of Henan University of Science and Technology(2015XTD001)
文摘Density functional calculations were used to investigate the structural,electronic,optical and thermal properties of Cr_4AlB_6.The optimized lattice constants and atomic positions accord well with the experimental data.The analysis of band structure and density of states confirms the metallic nature of Cr_4AlB_6.The static dielectric constant e1（0） is about 128.0,and the maximum optical conductivity occurs at about 8.12 eV.In the photon energy range from 7.87 to 23.48 e V,Cr_4AlB_6 presents a metal reflective property.The plasma resonance frequency wp of Cr_4AlB_6 is at the photon energy of 23.85 eV,and Cr_4AlB_6 will be transparent and change from metallic to dielectric response if the incident light has frequency greater than the plasma frequency of Cr_4AlB_6.Thermodynamic properties including the primitive cell volume and thermal expansion,the bulk modulus and heat capacity Cv were further investigated with the increasing temperature and pressure by using the quasi-harmonic Debye model.
文摘Using the time-dependent multilevel approach, we have calculated the coherent population transfer between the quantum states of potassium atom by a single frequency-chirped laser pulse. The result shows that a pair of sequential ＇broadband＇ frequency-chirped laser pulses can efficiently transfer population from the initial state of the ladder system to the target state. It is also found that the population can be efficiently transferred to a target state and trapped there by using an ＇intuitive＇ or a ＇counterintuitive＇ frequency sweep laser pulse in the case of ＇narrowband＇ frequency-chirped laser pulse. Our research shows that the complete population transfer is related to the pulse duration, chirp rate, and amplitude of the laser pulse.
