聚偏氟乙烯全反式分子链振动模式的研究

利用ab initio分子轨道计算,对β相聚偏氟乙烯(PVDF)的全反式分子链进行了结构优化,计算值和实验值基本符合,且发现C－C－C键角有两种不同的值,112.8°和113.3°.对该分子的频率进行了计算,得到了红外强度谱.在400～4 000 cm-1范围内,对30 μm厚的聚偏氟乙烯取向膜和取向极化膜进行了红外光谱的测量，红外吸收光谱和红外强度谱基本一致.把所有振动模式分成六个系列:系列Ⅰ（544～415 cm-1）,系列Ⅱ（913～792 cm-1）,系列Ⅲ（1 353～998 cm-1）,系列Ⅳ（1 458～1 361 cm-1）,系列Ⅴ和系列Ⅵ.其中只有系列Ⅲ能改变分子的电偶极矩,该系列振动模式和β相的PVDF的自发极化有着密切的关系.     

麻黄碱的密度泛函理论计算及拉曼光谱研究

用密度泛函理论B3LYP/6-311G++(d, p)方法优化了麻黄碱分子结构,计算了理论拉曼光谱,以此为依据,对麻黄碱的常规拉曼光谱进行了详细的指认,用Gaussview5.0软件对其峰位进行了详细的归属。采用了自组装方法,经氨基化处理后的玻片与银溶胶结合,获得了具有二维结构的纳米银基底,研究了沉积在基底表面麻黄碱的表面增强拉曼光谱,结果表明,实验所得拉曼光谱与理论计算拉曼光谱基本一致,该分子与银纳米表面化学吸附,苯环与银基底垂直。该研究为麻黄碱的快速、痕量检测提供了理论依据,也为冰毒类毒品拉曼光谱分析提供了重要参考。     

石墨烯基生物分子传感器件的第一性原理研究

基于第一性原理模拟, 我们构建了一种具有石墨烯电极的纳米间隙生物分子传感器件的理论模型. 研究发现,当碱基分子胞嘧啶、甲基化胞嘧啶和羟甲基化胞嘧啶分别通过器件时, 器件横向电流的大小差异约有1个数量级, 器件对此类分子具有一定的分辨能力. 分子之间的区分度大小受单链脱氧核糖核酸(DNA)中相邻碱基分子间的相互作用及碱基分子构型的影响. 研究工作表明, 此类石墨烯基分子传感器可准确高效地区分具有不同结构的碱基分子, 为准确定位DNA链中的变异碱基分子提出了一种新的思路.     

缺陷石墨烯吸附Au、Ag、Cu的第一性原理计算

采用基于密度泛函理论的投影缀加波方法研究了Au、Ag、Cu吸附在缺陷石墨烯单侧和双侧的体系,对吸附体系的吸附能、磁性、电荷转移和电子结构进行了计算和分析. 缺陷石墨烯吸附Au、Ag、Cu体系的吸附能比本征石墨烯增加2 eV以上,说明三种金属原子更容易吸附在缺陷位置;吸附体系的电荷密度差分和电子结构的结果表明,Au、Ag、Cu与缺陷石墨烯之间均为化学吸附. 计算吸附体系的磁性发现,单侧吸附时三种吸附体系均有磁性,磁矩大约为1μ_B;双侧吸附时,三种吸附体系磁矩大约为2μ_B.     

缺陷石墨烯吸附Au、Ag、Cu的第一性原理计算

采用基于密度泛函理论的投影缀加波方法研究了Au、Ag、Cu吸附在缺陷石墨烯单侧和双侧的体系,对吸附体系的吸附能、磁性、电荷转移和电子结构进行了计算和分析.缺陷石墨烯吸附Au、Ag、Cu体系的吸附能比本征石墨烯增加2 eV以上,说明三种金属原子更容易吸附在缺陷位置;吸附体系的电荷密度差分和电子结构的结果表明,Au、Ag、Cu与缺陷石墨烯之间均为化学吸附.计算吸附体系的磁性发现,单侧吸附时三种吸附体系均有磁性,磁矩大约为1μB;双侧吸附时,三种吸附体系磁矩大约为2μB.     

结合密度泛函理论的橙皮素及其包合物的红外和拉曼光谱研究

本文通过密度泛函理论(DFT)结合实验研究了橙皮素的红外和拉曼光谱,采用B3LYP/6-311+G(d,p)基组对其红外和拉曼光谱进行了计算,计算结果和实验结果基本一致。本文还利用红外及拉曼光谱对橙皮素与β-环糊精(β-CD)形成的包合物进行了分析,证明了橙皮素通过氢键作用嵌入β-CD的疏水空腔中而形成包合物,从而验证了拉曼光谱可以作为一种新型的验证包合物形成的方法。该研究为橙皮素及其包合物的鉴定提供了一种简单、快捷、无损测量的优良方法。     

基于新一代密度泛函和神经网络势能面的量子反应动力学计算

介绍了近年来发展起来的新一代密度泛函XYG3及利用神经网络构造分子体系势能面的最新进展。以H₃和CH₅等体系为实例,表明基于高效准确的密度泛函电子结构计算,与神经网络高精度势能面构造的理想结合,可以得到可靠的化学动力学结果,并有望用于更大更复杂的体系。     

基于第一性原理计算的铁电材料BaTiO3相关振动光谱指认

通过固相反应烧结法在1400 ℃下烧结4 h合成了BaTiO₃陶瓷, 并用X衍射确定了其为四方晶系. 进行了拉曼谱和红外谱的测量, 并采用洛仑兹函数以及四参数方法分别对上述光谱进行了拟合. 基于第一性原理的计算, 并考虑了横模纵模劈裂, 对拉曼和红外光谱进行了指认. 为了更好地分析振动模式, 所有振动模用群论的对称坐标进行了分解. 在12个光学模中, 仅具有拉曼活性的B₁模式是O4和O5沿着z轴的相对运动. A₁模式和E₁软模式是从立方BaTiO₃相的F_1u模式劈裂出来的, 对于四方相BaTiO₃的铁电性有着重要作用, 其体现在A₁⁽¹⁾模式造成了铁电z轴的极化, E₁模式导致了大介电常数. 这两个模式都可以看成是Ti 原子相对于O₆八面体笼子沿着z轴或者是xy平面的振动.     

密度泛函理论研究5-单苯基卟啉分子的几何结构和拉曼光谱

利用密度泛函理论(DFT)计算了5-单苯基卟啉(H2MPP)的几何结构和拉曼振动频率. 计算表明, 单个次甲基位置上的苯基取代降低了卟啉骨架大环的对称性. 苯基团取代对次甲基位置附近结构的影响较大, 而对吡咯环结构的影响较小. 计算给出的拉曼振动频率(校正因子为0.971)与实验测量数据吻合较好, 均方根误差(RMS)小于6.7 cm-1. 根据理论计算结果对实测拉曼光谱进行了指认, 计算分析和实验观察同时表明, 单个次甲基位置上的苯基取代导致卟啉大环的一些平面内简正振动, 如ν6、ν20、ν24和ν32等简正振动发生分裂. 分析认为其根本原因为单苯基取代导致的卟啉骨架大环对称性的降低.     

弱氢键作用对硫脲水溶液拉曼光谱影响的密度泛函理论计算

将拉曼光谱和密度泛函理论(DFT)计算结合能够把拉曼谱峰和分子结构及分子间氢键作用之间的变化联系起来, 反映分子周围的结构信息. 本文通过理论计算水分子和硫脲形成复合物的拉曼光谱, 并结合实验报道的拉曼光谱, 探究硫脲基频对分子局域结构的依赖性. 通过轨道分析, 发现水分子的氢键作用可以引起硫脲的前线轨道对易, 这将影响到硫脲的拉曼光谱性质. 最后计算也表明在中性水溶液中由于大的正Gibbs 自由能变, 硫脲不易发生异构转变.     

Vibrational Spectra and Density Functional Theory Calculations of Metallotriphenylcorroles

The infrared absorption and Raman scattering spectra were measured for the metallotriph-enylcorroles (MTPCs, M=Cu, Co, Ni, Mn). The ground-state structures and vibrational spectra of MTPCs have been calculated with the density functional theory. The observedRaman and IR bands have been assigned based on the calculation results. Due to the symmetry lowering, the vibrational spectra of MTPCs are much more complex than metal-loporphyrins, and several skeletal modes are found strongly coupled to the phenyl vibrations.The relationship between the Raman/IR frequencies and the structures of TPC ring is in-vestigated. It is found that the vibrations involving the C^I_αC^I_α stretch and C_αC_mstretch are sensitive to the size of corrole core. In particular, the frequency of υ₅, which is assigned to C^I_αC^I_α stretch in coupling with the C_αC_m symmetric stretch, increases linearly with the decrease of the corrole core-sizes and may be used as a mark band to evaluate the structural change of the metallocorroles.     

Vibrational Spectra and Density Functional Theory Calculations of Metallo-tetra-(tert-butyl)-tetra-azaporphyrines

The infrared absorption and 514.5 nm excited Raman spectra were measured for the metallo-tetra-(tert-butyl)-tetraazaporphyrin (MT(tBu)TAP, M=Cu, Co, Ni, Zn). The ground-state structures and vibrational spectra of MT(tBu)TAPs have been calculated at the B3LYP level of theory. The observed Raman and IR bands have been assigned based on the calculation results and by comparing with the normal metalloporphyrins. The relationship between the Raman/IR frequencies and the structures of TAP ring was investigated. The results show that the frequencies of C_βC_β′ stretch (A_g), asymmetric C_αN_m stretch (A_g), and symmetric C_αN_m stretch (B_g) modes increase linearly with the decrease of the core-sizes of TAP ring.Among the three modes, the later two are more sensitive to the core-size change.     

Vibrational Spectra and Quantum Calculations of Ethylbenzene

Normal vibrations of ethylbenzene in the first excited state have been studied using resonant two-photon ionization spectroscopy. The band origin of ethylbenzene of S₁←S₀ transition appeared at 37586 cm^-1. A vibrational spectrum of 2000 cm^-1 above the band origin in the first excited state has been obtained. Several chain torsions and normal vibrations are obtained in the spectrum. The energies of the first excited state are calculated by the time-dependent density function theory and configuration interaction singles (CIS) methods with various basis sets. The optimized structures and vibrational frequencies of the S₀ and S₁ states are calculated using Hartree-Fock and CIS methods with 6-311++G(2d,2p) basis set. The calculated geometric structures in the S₀ and S₁ states are gauche conformations that the symmetric plane of ethyl group is perpendicular to the ring plane. All the observed spectral bands have been successfully assigned with the help of our calculations.     

Vibrational spectrum of RbVOPO4

The infrared and Raman laser spectra of RbVOPO₄ were recorded and briefly discussed with the aid of factor group analysis. Some comparisons with the spectra of related materials were also made.     

Vibrational spectroscopic properties of botallackite-structure basic copper halides

Mid-infrared (4000-400 cm⁻¹) absorption and Raman (4000-95 cm⁻¹) spectra of the series of geometrically frustrated materials, botallackite-structure basic copper halides, α-Cu₂(OH)₃Cl and α-Cu₂(OH)₃Br polycrystalline samples were first, to the best of our knowledge, measured, respectively, to study the corresponding relationship between their vibrational spectral properties and crystal microstructures. Through the comparative analysis to the four spectra, the authors have definitely assigned or tentatively suggested the vibrational modes of hydroxyl groups in the trimeric hydrogen bond environment (OH)₃ Cl/Br, and atomic units O-Cu-O, Cu-O and Cl/Br-Cu-Cl/Br, etc. These results can be propitious to the low temperature spectral property of α-Cu₂(OH)₃Cl and α-Cu₂(OH)₃Br which must help to understand the underlying physics of their exotic geometric frustration phenomena at low temperatures.     

Molecular Dynamics Simulations of Silica Nanotube: Structural and Vibrational Properties Under Different Temperatures

Four-, six-, and eight-membered ring silica nanotubes at temperatures from 300 K to 1600 Kare relaxed by classical molecular dynamics simulations with three potential models. Thesimulation results indicate that the stability of the end rings of the three silica nanotubes gradually decreases with increase in temperature. The validity of the vibrational features of silica nanotubes is shown by the vibrational density of states. Infrared spectra on the silica nanotubes under different temperatures are investigated. A detailed assignment of each spectral peak to the corresponding vibrational mode of the three nanotubes has been addressed. The results are in good agreement with the other theoretical and experimental studies.     

优化迭代目标转换因子分析法在多组分混合物红外光谱解析中的应用

优化迭代目标转换因子分析法在多组分混合物红外光谱解析中的应用何锡文,陈鼎,王永泰（南开大学化学系、中心实验室,天津,３００００７１）关键词因子分析,相关性,红外光谱因子分析是一种多元统计方法,用其解析多组分混合物的红外光谱已有报道［１,２］。迭代目标...     

FT-IR, Raman and NMR Spectra, Molecular Geometry, Vibrational Assignments, ab initio and Density Functional Theory Calculations for Diethyl Phthalate

Phthalate acid esters (PAEs) possess endocrine disruptive effects and can produce reproductive and developmental toxicities. In this paper, both experimental and theoretical studies on FT-IR, Raman and 1H NMR spectra of diethyl phthalate (DEP) have been carried out. The geometrical structure of DEP was optimized at the HF/6-31G*, HF/6-311G**, B3LYP/6-31G*, and B3LYP/6-311G** levels, respectively. The harmonic vibrational frequencies, IR intensity, Raman activity and 1H NMR chemical shifts have been computed at the B3LYP/6-31G* and B3LYP/6-311G** levels. Anharmonic corrections to frequencies were obtained by means of second-order perturbation theory (PT2) at the B3LYP/6-31G* level. Based on potential energy distribution (PED), the vibrational assignments have also been performed. The theoretical calculation values were compared with the experimental observations and the results indicate they are in excellent agreement.     

丙酮酸分子结构与振动光谱的密度泛函理论研究

用密度泛函方法BLYP、B3LYP和从头算Hartree-Fock(HF)方法在6-31G*基组水平上对丙酮酸分子的几何结构（甲基的重叠式和交错式两种构象）和振动光谱分别进行了优化和计算,并给出了各种频率所对应的红外强度及拉曼活性,对光谱进行了指认。结果表明：在丙酮酸分子的两种构象中,重叠式比较稳定*B3LYP计算得到的构型参数与实验结果比较一致;在振动频率的计算中,BLYP未标度力场所计算的非CH3伸缩振动基频预测值和实验值的平均绝对偏差为10.4cm-1;而HF标度力场的平均绝对偏差为17.9cm-1。说明两者的结果与实验观测频率比较吻合,但B3LYP的频率计算值偏差（38.3cm-1）较大。根据振动频率的势能分布和红外光谱强度对此分子的振动基频进行了理论归属。