共查询到16条相似文献,搜索用时 125 毫秒
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采用密度泛函方法(DFT)和含时密度泛函方法(TDDFT)在B3LYP/6-311+G(d,p)基组水平上优化计算了在不同外电场作用下4-溴苯酚分子的物理性质,包括键长、键角、分子体系总能量、偶极矩、能隙、红外光谱、解离特性以及激发态.研究表明在外电场(0~0.03 a.u.)作用下,4-溴苯酚分子结构有明显的变化,随... 相似文献
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采用混合密度泛函理论中的B3LYP方法,并结合6-31G(d)、6-31G(df,p)、6-31+G(d)和6-311+G(2d,2p)四种基组,首次系统地计算了蛋氨酸在空气、四氯化碳、四氢呋喃、水和模拟蛋白质环境中的几何结构、电离能和红外光谱.研究结果表明,在不同的基组和介质环境下,蛋氨酸的几何参数与晶体结构实验参数相比,其键长和键角的差值分别小于0.0271(A)和5.32°;但二面角相差12.04°~122.11°;在同一计算方法下,介质的介电常数越高,分子的单点能越低,电离能也越小,对应的主要振动频率随之减小,强度增大;蛋氨酸的电离能比组氨酸的计算结果高0.33eV~0.56eV.所有数据均显示,较高基组下的计算结果更接近实验值.该研究为深入探索叶绿素与蛋氨酸配位后在光反应中心中的功能与作用提供了理论参考依据. 相似文献
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采用了从头算分子轨道理论(MP2,非限性的二级微扰理论)和密度泛涵理论(B3LYP),分别在6-31G(d,p),6-311G(d,p),6-311+G(d,p),6-311G(2d,p),和6-311+G(2df,2p)基组上优化CH3-nFnO2-Li^+(n=0~3)的几何结构,计算出了相关的NBO电荷分布和锂离子相对于自由基CH3-nFnO2的亲和能。并在同一水平上计算了自由基CH3-nFnO2和络合物CH3-nFnO2-Li^+的相关伸缩振动频率。CH3-nFnO2在UB3LYP/6-311G(d,P)得到的振动频率与实验值符合得很好.根据相关的文献报道,我们运用从头算分子轨道理论和密度泛涵理论计算出的锂离子相对于CH3-nFnO2的亲和能都能够表明络合物CH3-nFnO2-Li^+在气态下能以一种稳定的物种形态被离子附着质谱检测. 相似文献
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利用355nm激光作为光源对间甲苯酚分子进行了多光子电离解离研究,得到了间甲苯酚分子的多光子电离飞行时间质谱图,实验中没有观测到母体离子信号。对其中的部分产物离子进行分析,得出了该波长下主要的解离电离通道。应用从头计算理论,在B3LYP/6-311++G(d,p)基组水平上对质荷比为109(C7H8OH+)离子及C7H8O的可能构型进行优化,得到了其稳定构型。对C7H8OH+离子势能面的研究得到,C7H8OH+离子的形成是一个无势垒的反应过程。 相似文献
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氯溴双卤代烷烃在太阳紫外光辐射下解离生成游离态的氯和溴自由基,它们是破坏臭氧的主要元凶之一。利用B3LYP/6-311++G(d,p)方法对氯溴双卤代烷烃分子CnH2nBrCl(n=1~16)进行分子构型优化以及红外光谱的计算。根据数据进行分析比较,得到了氯溴双卤代烷烃C-Br键和C-Cl键的键长、键角等构型参数随烷基支链长度增加(n为1~16)的变化趋势图。研究讨论了氯溴双卤代烷烃的红外光谱相关振动随烷基支链长度增加的重要变化规律。 相似文献
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Yuxi Sun Zengwei Liu Cheng Yu Changliang Huang Qingli Hao Laixiang Xu 《Organic Electronics》2013,14(6):1538-1550
In recent years, the imine-bridged organics has been one of the hot spots in the field of photo-responsive materials. Herein, N-(5-chloro-2-hydroxyphenyl)-(3-bromo-6-oxocyclohexa-2,4-dienylidene)-methylamine (CHPBOCDMA) was synthesized and characterized by a combined experimental and theoretical method. CHPBOCDMA adopts trans configuration about the central methylamine bond. The vibrational spectral bands were assigned to the molecular structure in details. The vibrational spectrum has been recorded and analyzed. Theoretic calculations provide the parameters of thermodynamics, NLO, atomic charges, frontier molecular orbitals and natural bond orbitals. The mean linear polarizability and first-order hyperpolarizability calculated at B3LYP/6-311+G(d,p) level are of 36.4292 Å3 and 45.0911 × 10?31 cm5/esu, respectively. CHPBOCDMA is a molecular semiconductor by seven directional batteries connected in a parallel–series mode, which can transport electrons in a long range. The HOMO and LUMO orbitals with the energy gap of 3.059 eV are responsible for the optical and electron-transfer properties of the studied compound. The photoresponse-related results indicate the compound will be an excellent organic candidate of photon-responsive materials. 相似文献
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N.A. Zaidi J.P. Foreman G. Tzamalis S.C. Monkman A.P. Monkman 《Advanced functional materials》2004,14(5):479-486
The oxidative polymerization of aniline hydrochloride derivatives in water at low temperature is studied without lithium chloride. The resulting polymers have high molecular weight but the conductivity of the acid‐doped films is strongly dependent on the alkyl‐substituted chain at the 2‐positions. The root cause of the alkyl‐substitution effects is thoroughly investigated using density functional theory (DFT) methods (B3LYP using 6–1G(d,p) and 6‐311++G(2d,2p) basis sets). Internal structural changes observed on substitution appear to be more significant than a variety of electronic parameters measured using the natural bond orbital (NBO) method. Interplanar angles steadily increase on substitution, whereas ring orbital properties and the amount of ring delocalization remain fairly constant. An investigation into the extent to which lone pair–σ‐orbital overlap is affected by substitution indicates that increasing the steric bulk of the substituent reduces the ability of the lone pair to delocalize into the ring orbitals. However, the amount of overlap between the two is not adversely affected until the dihedral between them is > 30°, a situation that only occurs in i‐propyl and s‐butyl substitution. This finding is completely reflected in the experimental conductivity measurements. 相似文献
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选择C20富勒烯分子最可能稳定存在的几种等能异构构型作为研究对象,在高斯中选用密度泛函理论,用B3LYP/6-31G*方法和基组对这几种分别属于D2h、C2h、C2、D3d和Ci对称群的C20富勒烯分子异构体进行了结构优化,得到了各个构型的键长信息并对它们进行了比较。根据对称性的不同对5种异构体分子的13C NMR谱图特征进行了分析和比较,阐述了每种异构体的NMR谱图特征线的数目以及强度差别。结果表明,通过观察C20富勒烯分子异构体13C NMR谱图中特征谱线的个数和强度,可以很好地区分5种异构体的异构类型,为实验上鉴定C20富勒烯分子所属对称群做了前期准备。 相似文献
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进行了有机紫外半导体N-[5-甲基-1,3,4-噻二唑-2-取代]二硫代氨基甲酸钾(PMTC)的制备及FT-IR、Raman、UV-Vis及PL光谱实验表征。对实验测试FT-IR及Raman光谱的振动峰进行了归属,Raman光谱测试发现S-K在152 cm-1有v(S-K-S)伸缩振动。UV-Vis实验光谱表明PMTC在200~350nm波段有紫外吸收,PL实验光谱表明PMTC在340~400 nm波段有明显的紫外发光峰,峰值波长为373 nm,PL谱相对于吸收光谱有Stokes频移。采用密度泛函理论(DFT)方法对PMTC进行了B3LYP/6-31G水平上的分子结构优化、UV-Vis光谱、分子前线轨道、分子电子密度、Mulliken电荷等理论计算。理论研究结果表明:PMTC在UV-Vis波段有三个电子跃迁吸收。前线轨道计算表明PMTC的HOMO的电子主要分布在与K原子相连的两个S原子上,而LUMO轨道的电子主要集中在K原子上,PMTC吸收光子后,产生电子由HOMO至LUMO跃迁的实质是电子由配体(主要是配位S原子)向金属原子K的转移。 相似文献