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81.
Unitary group adapted state specific multireference perturbation theory: Formulation and pilot applications 下载免费PDF全文
Avijit Sen Sangita Sen Pradipta Kumar Samanta Debashis Mukherjee 《Journal of computational chemistry》2015,36(9):670-688
We present here a comprehensive account of the formulation and pilot applications of the second‐order perturbative analogue of the recently proposed unitary group adapted state‐specific multireference coupled cluster theory (UGA‐SSMRCC), which we call as the UGA‐SSMRPT2. We also discuss the essential similarities and differences between the UGA‐SSMRPT2 and the allied SA‐SSMRPT2. Our theory, like its parent UGA‐SSMRCC formalism, is size‐extensive. However, because of the noninvariance of the theory with respect to the transformation among the active orbitals, it requires the use of localized orbitals to ensure size‐consistency. We have demonstrated the performance of the formalism with a set of pilot applications, exploring (a) the accuracy of the potential energy surface (PES) of a set of small prototypical difficult molecules in their various low‐lying states, using natural, pseudocanonical and localized orbitals and compared the respective nonparallelity errors (NPE) and the mean average deviations (MAD) vis‐a‐vis the full CI results with the same basis; (b) the efficacy of localized active orbitals to ensure and demonstrate manifest size‐consistency with respect to fragmentation. We found that natural orbitals lead to the best overall PES, as evidenced by the NPE and MAD values. The MRMP2 results for individual states and of the MCQDPT2 for multiple states displaying avoided curve crossings are uniformly poorer as compared with the UGA‐SSMRPT2 results. The striking aspect of the size‐consistency check is the complete insensitivity of the sum of fragment energies with given fragment spin‐multiplicities, which are obtained as the asymptotic limit of super‐molecules with different coupled spins. © 2015 Wiley Periodicals, Inc. 相似文献
82.
Jiri Kudr Sylvie Skalickova Lukas Nejdl Amitava Moulick Branislav Ruttkay–Nedecky Vojtech Adam Rene Kizek 《Electrophoresis》2015,36(19):2367-2379
Nanofluidics is becoming an extensively developing technique in the field of bioanalytical chemistry. Nanoscale hole embed in an insulating membrane is employed in a vast variety of sensing platforms and applications. Although, biological nanopores have several attractive characteristics, in this paper, we focused on the solid‐state nanopores due to their advantages as high stability, possibility of diameter control, and ease of surface functionalizing. A detection method, based on the translocation of analyzed molecules through nanochannels under applied voltage bias and resistive pulse sensing, is well established. Nevertheless, it seems that the new detection methods like measuring of transverse electron tunneling using nanogap electrodes or optical detection can offer significant additional advantages. The aim of this review is not to cite all related articles, but highlight the steps, which in our opinion, meant important progresses in solid‐state nanopore analysis. 相似文献
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Fredrik Elwinger Sergey V. Dvinskikh István Furó 《Magnetic resonance in chemistry : MRC》2015,53(8):572-577
A method for measuring the ligand concentration in heterogeneous materials like chromatography media is described. In this method, 13C single pulse excitation magic angle spinning NMR experiment with broadband 1H decoupling is used to determine the peak integrals for a butyl ligand in the spectrum of a dried chromatography medium. Within a carefully controlled protocol, those integrals compared with that of the internal reference compound dimethyl sulfone provide the required volume concentration with an accuracy of ca 2%. The effects of temperature, degree of hydration, and other experimental parameters are discussed. Copyright © 2015 The Authors. Magnetic Resonance in Chemistry published by John Wiley & Sons Ltd. 相似文献
86.
Prof. Dr. Holger Braunschweig Charlotte Brückner Dr. Mehmet Ali Celik Dr. Klaus Dück Dr. Florian Hupp Dr. Thomas Kramer Johannes Krebs Dr. Ivo Krummenacher 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(31):11056-11064
Taking advantage of an improved synthesis of [Ti(η6‐C6H6)2], we report here the first examples of ansa‐bridged bis(benzene) titanium complexes. Deprotonation of [Ti(η6‐C6H6)2] with nBuLi in the presence of N,N,N′,N′′,N′′‐pentamethyldiethylenetriamine (pmdta) leads to the corresponding 1,1′‐dilithio salt [Ti(η6‐C6H5Li)2] ? pmdta that enables the preparation of the first one‐ and two‐atom‐bridged complexes by simple salt metathesis. The ansa complexes were fully characterized (NMR spectroscopy, UV/Vis spectroscopy, elemental analysis, and X‐ray crystallography) and further studied electrochemically and computationally. Moreover, [Ti(η6‐C6H6)2] is found to react with the Lewis base 1,3‐dimethylimidazole‐2‐ylidene (IMe) to give the bent sandwich complex [Ti(η6‐C6H6)2(IMe)]. 相似文献
87.
Selective Probing of Gaseous Ammonia Using Red‐Emitting Carbon Dots Based on an Interfacial Response Mechanism 下载免费PDF全文
Dr. Bang‐Ping Jiang Bo Zhou Prof. Dr. Xing‐Can Shen Yun‐Xiang Yu Dr. Shi‐Chen Ji Chang‐Chun Wen Prof. Dr. Hong Liang 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(52):18993-18999
Solid‐state fluorescence sensing is one of the most appealing detection techniques because of its simplicity and convenience in practical operation. Herein, we report the development of a red‐emitting carbon dots (RCDs)‐based material as a solid‐state fluorescence sensor for the selective probing of gaseous ammonia. The RCDs were prepared by a low‐cost, one‐step carbonization method using sugar cane bagasse as the carbon precursor. The pristine RCDs were then directly coated on polyvinylidene fluoride membrane to produce a new fluorescence sensor capable of selectively distinguishing toxic gaseous ammonia from other analyte vapors through sensitive fluorescence quenching with a low detection limit. More importantly, the interfacial response mechanism occurring on the surface of the RCDs has been studied by X‐ray photoelectron spectroscopy, Fourier‐transform infrared spectroscopy, and Raman measurements. The results indicate that fluorescence quenching in the RCDs might result from ammonia‐induced Michael addition through insertion of N into the C?C group and deprotonation of the carboxyl group. To the best of our knowledge, this is the first report that provides clear insight into the mechanism of surface chemistry on CDs in the solid state. 相似文献
88.
Frontispiece: A Step‐by‐Step Assembly of a 3D Coordination Polymer in the Solid‐State by Desolvation and [2+2] Cycloaddition Reactions 下载免费PDF全文
89.
Yahui Zhang Lingwei Kong Jianbing Shi Bin Tong Junge Zhi Xiao Feng Yuping Dong 《中国化学》2015,33(7):701-704
A new type of AIE molecules based on hexaphenyl‐1,3‐butadienes was reported with respect to the synthesis and characterization. This material exhibited different maximum emission wavelength and enhanced emission intensity at different aggregate state (amorphous and crystalline state). 相似文献
90.
本文采用Reax FF-lg分子反应性力场研究了六硝基六氮杂异伍兹烷(CL-20)和苯并三氧化呋咱(BTF)形成的共晶在冲击波加载下的反应情况。结果发现:冲击波速度为Us=9 km·s-1时,含能分子快速分解。冲击加载在不同方向上时,分解速率不同,冲击波沿X轴方向时分解最快。反应早期主要是N-NO2键的断裂,生成NO2。较大分子质量的团簇会出现在反应前期,随着反应的进行团簇数量增加。整个模拟过程中,主要产物N2的数目有较大波动,28 ps达最大值。冲击波速度对反应后期的影响较小。 相似文献