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通过搜索和调查固化材料的最优包容量,并利用密度泛函理论(DFT)对固化材料晶体进行了优化和预测,对锆石中核素原子包容量(x)进行了讨论,对相应的结构性能进行了研究,包括焓的形成、晶格畸变和态密度(DOS)。分别选择了高容量包晶(硅酸锆)和高稳定性能的晶体(Zr2Gd2O7)锆石为基本晶体,研究其固化性能。对高包容量晶的计算结果显示铈(Ce)或铀(U)原子放大能扩展硅酸锆的晶格长度,并导致形态从Fm3m形态转变为I41/AMD,使相对应的态密度远离Fermi能级。Ce和U原子在Zr1-xCe(或U)xSiO4基质中最佳包容量分别为25%和30%。这些数据与实验数据相吻合。 相似文献
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The thermodynamic properties of 135 polybrominated dibenzothiophenes (PBDTs) in the gaseous state at 298.15 K and 1.013×105 Pa, are calculated using the density functional theory (the B3LYP/6-311G**) with Gaussian 03. Based on these data, the isodesmic reactions are designed to calculate the standard enthalpy of formation (ΔfH1257;) and the standard Gibbs energy of formation (ΔfG1257;) of PBDTs. The relations of these thermodynamic parameters with the number and position of bromine substituents (NPBS) are discussed, and it is found that there exist good correlations between thermodynamic parameters (including heat capacity at constant volume, entropy, enthalpy, free energy, ΔfH1257;, ΔfG1257;) and NPBS. The relative stability order of PBDT congeners is proposed theoretically based on the relative magnitude of their ΔfG1257;. In addition, the values of molar heat capacities at constant pressure (Cp,m) for PBDT congeners are calculated. 相似文献
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In the present study, the density functional theory method with various basis sets for optimizing and computing the structural and energetic properties of octasilacubane were performed at 298.15 K and 1 atmosphere. The data from the calculations on this compound show us the internal angles in the structure are 90 degrees. For this reason, the molecule has serious angular pressure. This angular strain is tolerated by a higher percentage of p-orbitals of silicon atoms in the Si-Si σ-bonds formation. According to calculation, σ (Si?Si) bonds in the octasilacubane system are formed from an sp3.44 d 0.02 hybrid. Also, IR and NMR spectra of the structure were simulated. The electronic chemical potential, the hardness and electrophilicity power of the molecule were obtained from frontier orbitals energies. The data show the structure has low electrophilicity. Heats of formation and detonation parameters were then calculated at studied levels of B3LYP (Becke, 3 parameter, Lee-Yang-Parr) theory. The simulation results revealed that this compound because for its high molecular weight is not a viable candidate of high energy density materials (HEDMs). 相似文献
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The density functional theory, simplified by the local density approximation and mean-field approximation, is applied to study the surface properties of pure non-polar fluids. A reasonable long rang correction is adopted to avoid the truncation of the potential. The perturbation theory is applied to establish the equation for the phase equilibrium, in which the hard-core chain fluid is as the reference fluid and the Yukawa potential is used as the perturbation term. Three parameters, elk, d and ms, are regressed from the vapor-liquid equilibria, and the surface properties, including density profile, surface tension and local surface tension profile are predicted with these parameters. 相似文献
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在密度泛函理论(DFT)的B3LYP/6-31G^*水平上对一系列靛族染料化合物的几何构型进行优化计算:在获得基态稳定结构的基础上,应用含时密度泛函理论(TD-DFT)在相同水平下计算其电子吸收光谱,探讨了不同给电子基团和发色体系的延伸对电子吸收光谱的影响,得到了与实验基本一致的变化规律。结果表明,给电子能力的增强和发色体系的纵向延伸均使光谱产生一定红移,通过对前线轨道组成进行自然布居分析,揭示了靛族染料的发光均源自分子中HOMO-LUMO(П→П^*)电子跃迁。 相似文献
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采用Politzer经验公式,运用密度泛函理论研究了升华焓的预估方法。基于在B3LYP/6–31G**水平上获得56种化合物稳定构型的基础上,运用Multiwfn软件对分子表面进行了定量分析。对比研究了采用Politzer系数和Rice系数对升华焓预估值的影响,结果表明,Politzer系数和Rice系数所造成的最大误差分别为46.1 kJ/mol和38.9 kJ/mol。为了缩小误差,根据34种化合物升华焓的实验值拟合出了一组新的系数(0.000 409(α),2.005 0(β),–2.82(γ)),并用来计算了22种含能化合物的升华焓。计算结果表明,该组新系数使计算值的最大误差为32.6 kJ/mol,标准偏差为13.8 kJ/mol。 相似文献
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《化学世界》2017,(2)
为了深入了解非晶态合金Co-Fe-B的结构特点以及磁学性质,利用密度泛函数理论(DFT)方法,在B3LYP/Lan12dz水平下,对团簇Co_2FeB_2和CoFe_2B_2的十余种可能存在的构型在不同重态下进行全参数优化计算和频率验证,共得到17种不同构型,分别是三角双锥型、戴"帽"三角锥型、四方锥型以及平面型。对这些稳定构型的结构特点以及磁学性质进行研究分析,结果表明:团簇CoFe_2B_2比团簇Co_2FeB_2更具有结构多样性,而且各化学键的配置更加均匀、合理;在两团簇各构型中,二、三、四重态下的Co原子的磁矩非常接近,Fe原子的磁矩也是如此,且Co和Fe原子对磁性的贡献均较高;单重态下的Co和Fe原子对磁性的贡献较低;Fe原子对磁性的贡献大于Co原子的。 相似文献
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运用量子化学密度泛函理论B3LYP/6-31G*方法对脱苯[15]轮烯和脱氢苯吡啶[15]轮烯进行了优化,用含时密度泛函(TD-DTF)计算其吸收光谱,结合前线分子轨道讨论吸收波长不同的原因。结果表明,三种构型的分子为平面共轭分子,分子Ⅰ的苯环被吡啶环取代成分子Ⅱ和Ⅲ,分子Ⅲ的最大吸收波长最长;分子Ⅱ最大吸收波长最短。 相似文献
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采用乙二醇还原法制备了Pt颗粒粒径为6 nm的Pt/Al2O3催化剂,借助密度泛函理论(DFT)计算的动力学参数,建立了Pt(111)面上的微观反应动力学模型,并在此基础上建立了Pt(111)面上的Langmuir-Hinshelwood Hougen-Watson(LHHW)模型。结果表明:丙烷脱氢对丙烷的反应级数是1.00级,对氢气的反应级数是-0.51级;反应的表观活化能约为80 kJ/mol;在Pt(111)面上,氢原子是最丰富的表面吸附物种,丙烷脱氢速率受第二步脱氢控制。 相似文献
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William N. Setzer 《International journal of molecular sciences》2009,10(8):3488-3501
A conformational analysis of nine macrocyclic thioether musks has been carried out using molecular mechanics (MMFF), density functional theory (DFT) using both B3LYP and M06 functionals, as well as Hartree-Fock and post-Hartree-Fock (MP2) ab initio methods. 6-Thia-, 10-thia- and 4-methyl-5-thia-14-tetradecananolide, 4-thia-, 7-thia-, 11-thia- and 12-thia-15-pentadecanolide and 6-thia- and 12-thia-16-hexadecanolide were modeled. Unfortunately, there was little agreement between the computational methods at the levels of theory used in this study. 相似文献