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91.
92.
严继民 《中国科学B辑(英文版)》1990,(7)
An ab initio calculation of the hydrogen bond complex (HF)_2 is given with the 6-311 G~(**) basis set, according to which the potential surface around the balance point of the distancès and the orientations between two HF molecules is obtained. The atomic charges in the system are calculated with the PD/LSF method (potential-derived/least-square-fitting method) and then an analysis of the hydrogen bond interaction between two HF molecules is given with the (exp-6-1) potential function, by means of which it is shown that the main interaction between them is not an electro-static but a charge transfer one. The potential curve between two HF molecules is like a Morse function. 相似文献
93.
Moreno M. M. Torres Santos R. H. A. Gambardella M. T. P. Camargo A. J. da Silva A. B. F. Trsic M. 《Structural chemistry》1998,9(5):365-373
The crystal and molecular structures of the following molecules have been determined: 1-acetyl-indoline, 1-acetyl-5-nitro-indoline, l-acetyl-5-nitro-7-bromo-indoline, 1-acetyl-5-bromo-7-nitroindoline, and l-acetyl-5-bromo-7-nitro-indol. Molecular orbital calculations are performed for these compounds and two related species. 相似文献
94.
Carlos?AlemánEmail author Jordi?CasanovasEmail author 《Colloid and polymer science》2004,282(6):535-543
A theoretical study based on force-field calculations has been performed to investigate the structural preferences of crystalline even nylons n with large and very large aliphatic segments. Atomistic energy calculations and Monte Carlo simulations were carried out considering the conventional and forms of nylons 10, 12, 18, 24, and 32. Results indicated that the form is the most favored for nylons 10, 12, 18, and 24. However, the structure was unstable for nylon 32, a polymer in which the density of hydrogen bonds is almost negligible. In this case, the arrangement is energetically more favored than the one. 相似文献
95.
Density functional calculations were performed on bonding and structural features of [(ηn-BH4)TM(CO)4]− (n = 1, 2, 3; TM = Cr, Mo) complexes. Calculations show that the ground state is bidentate which is in good agreement with experimental results. It has been found that the bridge and terminal hydrogen atoms will interchange by two pathways: (i) twist of BH4 about one of the bridge B-H and (ii) twist of BH4 about one of the terminal B-H. The molecular orbital calculations and natural bond orbital methodologies for different isomers of these complexes have been evaluated. The final results indicate that case (i) is more preferable relative to another case. 相似文献
96.
The calculations of clusters modeling the fluorine-doping and oxygen deficiency of YBa2Cu307 have been performed by the method of all-electronab initio Hartree-Fock with self-consistent crystal field. Results show that in CuO planes electric charge significantly increases,
the chemical valence of Cu decreases and the covalent bonding of Cu-O greatly weakens owing to oxygen deficiency, while the
effect of F restores the local electronic structure of YBa2Cu3O7. The reported opinion that F occupied the oxygen vacancy in Cu-O chains seems disputable according to the calculated bonding
characteristics
Project supported by the National Natural Science Foundation of China. 相似文献
97.
水煤气变换反应的微观动力学分析──Cu基催化剂上H_2S中毒失活原因的 Monte Carlo 模拟研究 总被引:1,自引:0,他引:1
用BOCMP方法及MonteCarlo模拟技术,对H2S导致Cu基催化剂失活的原因进行了计算分析。研究结果表明,当原料气中存在H2S时,WGS反应的活化能明显高于无H2S时的活化能,随着表面H2S浓度的增大(θ=0,0.10,0.25),反应的活化能也逐渐变大(其大小比为1∶1.34∶3.3),究其原因可归结为H2S的存在使得反应物分子的吸附热减小,从而使H2O的解离吸附(WGS反应的速控步骤)活化能增大。 相似文献
98.
对于NO分子轨道的能级次序现有两种不同的说法,不少人根据NO与O_2~+是等电子体,由O_2~+分子的能级次序确定NO分子组态。本文用NO和O_2~(+)从头计算结果以及NO的紫外光电子能谱相结合的方法说明NO的5σ轨道是弱成键轨道,5σ的轨道能稍高于1π轨道能,也就是说NO的能级次序是与N_2分子相同的;NO与O_2~+虽是等电子体,但是能级次序并不相同,因此由O_2~+的能级次序确定NO分子的电子组态是不妥的。 相似文献
99.
Electron and photon reflection ratios (in number and energy) for absorbers bombarded by electrons have been computed with the ITS Monte Carlo system version 3. Electrons of energies from 0.1 to 100 MeV have been assumed normally incident on an effectively semi-infinite absorber. The absorbers considered are elemental solids of atomic numbers from 4 to 92. The data on the electron reflection ratios agree rather well with the experimental data collected from literature except some discrepancies when the number-reflection ratio is small. For photons, the number-reflection ratio increases with increasing energy, but the energy-reflection ratio shows a maximum around 10 MeV. Empirical equations for the electron reflection ratios and the photon energy-reflection ratio are given (for electrons, graphs only). 相似文献
100.