生长溶液配比对MnTeMoO6晶体形态的影响

采用顶部籽晶溶液法生长Mn Te Mo O6晶体,研究了在不同配比生长溶液中Mn Te Mo O6晶体的实际生长形态,模拟计算了Mn Te Mo O6晶体的理想生长形态,探讨了生长溶液配比对晶体形态的影响,选择的3种生长溶液中Mn Te Mo O6∶Te O2∶Mo O3摩尔比分别为1∶2∶2、1∶3∶2和1∶3∶3。结果表明,在3种配比的生长溶液中Mn Te Mo O6晶体的(110)面具有最大的面网密度和最小的生长速率;生长溶液中Te O2和Mo O3的含量和比例影响了晶体在不同方向的生长速率,从而影响到Mn Te Mo O6晶体的实际生长形态。     

He原子与HF分子碰撞截面的量子力学计算

用量子力学密耦近似方法计算了入射氦原子能量E=88?meV时,He-HF碰撞,弹性散射分波截面(00-00)和非弹性散射00-01及00-02分波截面.计算结果与公认较好的Moszynski等人的SAPT势比较接近.     

空气污染组分H2O和CO2对乙烯燃烧性能的影响(II)——反应机理和动力学模拟

超燃冲压发动机在高空工作时, 以高温高速纯净空气作氧化剂使燃料燃烧. 但在地面实验中, 高温空气往往通过燃烧加热方式获得, 会使空气中含有H2O和CO2等污染组分. 本文用活塞流反应器进行动力学模拟, 研究在不同初温、压强和燃气比的条件下, H2O和CO2污染组分对乙烯燃烧的温度、压强和点火延迟时间等特性的影响. 模拟结果表明: 乙烯在含有H2O/CO2污染物的空气中燃烧, 相比纯净的空气而言, H2O对乙烯的点火有一定的促进作用, 而CO2有一定的抑制作用; 空气中含H2O和CO2污染物使乙烯燃烧的平衡温度和压强降低, 在污染物浓度相同时, CO2引起的下降幅度比H2O的大. 模拟结果能较好地解释现有的实验现象.     

Computation of Bond Dissociation Energies for Removal of Nitrogen Dioxide Groups in Certain Aliphatic Nitro Compounds

Bond dissociation energies for removal of nitrogen dioxide groups in 10 aliphatic nitro compounds, including nitromethane, nitroethylene, nitroethane, dinitromethane, 1-nitropropane, 2-nitropropane, 1-nitrobutane, 2-methyl-2-nitropropane, nitropentane, and nitrohexane, are calculated using the highly accurate complete basis set （CBS-Q） and the three hybrid density functional theory （DFT） methods B3LYP, B3PW91 and B3P86 with 6-31G^＊＊ basis set. By comparing the computed bond dissociation energies and experimental results, we find that the B3LYP/6-31G^＊＊ and B3PW91/6-31G^＊＊ methods are incapable of predicting the satisfactory bond dissociation energy （BDE）. However, B3P86/6-31G^＊＊ and CBS-Q computations are capable of giving the calculated BDEs, which are in extraordinary agreement with the experimental data. Nevertheless, since CBS-Q computational demands increase rapidly with the number of containing atoms in molecules, larger molecules soon become prohibitively expensive. Therefore, we suggest to take the B3P86/6-31G^＊＊ method as a reliable method of computing the BDEs for removal of the NO2 groups in the aliphatic nitro compounds.     

The evaluation of bond dissociation energies for NO2 scission in nitro compounds using density functional and complete basis set methods

By using the density functional theory （B3LYP） and four highly accurate complete basis set （CBS-Q, CBS-QB3, CBS-Lq, and CBS-4M）ab initio methods, the X（C, N, O）-NO2 bond dissociation energies （BDEs） for CH3NO2, C2H3NO2, C2H5NO2, HONO2, CH3ONO2, C2H5ONO2, NH2NO2 （CH3）2NNO2 are computed. By comparing the computed BDEs and experimental results, it is found that the B3LYP method is unable to predict satisfactorily the results of bond dissociation energy （BDE）; however, all four CBS models are generally able to give reliable predication of the X（C, N, O）-NO2 BDEs for these nitro compounds. Moreover, the CBS-4M calculation is the least computationally demanding among the four CBS methods considered, Therefore, we recommend CBS-4M method as a reliable method of computing the BDEs for this nitro compound system.     

Potential Energy Surfaces of Nitrogen Dioxide for the Ground State

The potential energy function of nitrogen dioxide with the C2v symmetry in the ground state is represented using the simplified Sorbie-Murrell many-body expansion function in terms of the symmetry of NO2. Using the potential energy function, some potential energy surfaces of NO2（C2v, X^-^2A1）, such as the bond stretching contour plot for a fixed equilibrium geometry angle θ and contour for O moving around N-O （R1）, in which R1 is fixed at the equilibrium bond length, are depicted. The potential energy surfaces are analysed. Moreover, the equilibrium parameters for NO2 with the C2v, Cs and Dsn symmetries, such as equilibrium geometry structures and energies, are calculated by the ab initio （CBS-Q） method.     

Potential energy surfaces of ozone in the ground state

Equilibrium parameters of ozone, such as equilibrium geometry structure parameters, force constants and dissociation energy are presented by CBS-Q {\it ab initio} calculations. The calculated equilibrium geometry structure parameters and energy are in agreement with the corresponding experimental values. The potential energy function of ozone with a C离解能;空气;能量表面;地面ozone, potential energy surface, barrier, dissociation energyProject supported by the National Natural Science Foundation of China (Grant Nos~10376021 and 10676025), and the Scientific Research Fund of Sichuan Provincial Education Department, China (Grant No~2006A131).2006-10-08Equilibrium parameters of ozone, such as equilibrium geometry structure parameters, force constants and dissociation energy are presented by CBS-Q ab initio calculations. The calculated equilibrium geometry structure parameters and energy are in agreement with the corresponding experimental values. The potential energy function of ozone with a C2v symmetry in the ground state is described by the simplified Sorbie-Murrell many-body expansion potential function according to the ozone molecule symmetry. The contour of bond stretching vibration potential of an O3 in the ground state, with a bond angle （θ） fixed, and the contour of O3 potential for O rotating around O1-O （R1）, with O1-O bond length taken as the one at equilibrium, are plotted. Moreover, the potentials are analysed.     

空气污染组分H2O和CO2对乙烯燃烧性能的影响

超燃冲压发动机在高空工作时, 以高温高速纯净空气作氧化剂使燃料燃烧. 但在地面实验中, 高温空气往往通过燃烧加热方式获得, 从而使空气包含了H2O和CO2污染组分. 本文用电阻加热来流空气并添加污染组分的方法, 研究了燃烧室模型中乙烯的燃烧状态和壁面压力受污染组分的影响. 用化学反应动力学模拟的方法, 在绝热刚性反应器模型中用H2O和CO2取代空气中的N2, 研究了污染组分对点火延迟和燃烧温度的影响, 并从链反应机理的角度讨论了实验和动力学模拟结果.     

He原子与HF分子碰撞截面的量子力学计算

用量子力学密耦近似方法计算了入射氯原子能量E=88meV时，He—HF碰撞，弹性散射分波截面(00-00)和非弹性散射00-01及00—02分波截面。计算结果与公认较好的Moszynski等人的SAPT势比较接近。     

碳氢燃料热裂解机理及化学动力学模拟

发动机设计中,燃烧室的热管理问题日益突出.其根源必然涉及到碳氢燃料的化学机理模型.讨论了大分子烃类燃料热裂解反应的反应类型,分析了各反应类型的详细动力学以及对热裂解反应的灵敏度、重要性.根据热裂解反应类型有限和基于物质的一维表示,开发了大分子烃类反应机理的自动生成程序ReaxGen.建立了相应的热、动力学数据库,探讨了如何建立碳氢燃料的详细热裂解化学动力学模型.最后我们建立了正庚烷热裂解反应的详细机理,并用该机理模型模拟预测了产物分布和转化率,理论上计算了热沉值.所得结果与文献结果进行对比讨论.