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81.
Based on different ab initio electronic structure calculations (CI-R12 and Gaussian Geminals) of the Born-Oppenheimer electronic energy E(BO) of H(3)(+) from high to highest quality, we build up a potential energy surface which represents a highly reliable form of the topology of the whole potential region, locally and globally. We use the CI-R12 method in order to get within reasonable CPU-time a relatively dense grid of energy points. We demonstrate that CI-R12 is good enough to give an accurate surface, i.e., Gaussian Geminals are not absolutely necessary. For different types of potential energy surface fits, we performed variational calculations of all bound vibrational states, including resonances above the dissociation limit, for total angular momentum J = 0. We clarify the differences between different fits of the energy to various functional forms of the potential surface. Small rms-values (<1 cm(-1)) of the fit do not provide precise information about the interpolatory behaviour of the fit functions. 相似文献
82.
We present here the implementation of a self-consistent approach to the calculation of excitation energies within regular Kohn-Sham density functional theory. The method is based on the n-order constricted variational density functional theory (CV(n)-DFT) [T. Ziegler, M. Seth, M. Krykunov, J. Autschbach, and F. Wang, J. Chem. Phys. 130, 154102 (2009)] and its self-consistent formulation (SCF-CV(∞)-DFT) [J. Cullen, M. Krykunov, and T. Ziegler, Chem. Phys. 391, 11 (2011)]. A full account is given of the way in which SCF-CV(∞)-DFT is implemented. The SCF-CV(∞)-DFT scheme is further applied to transitions from occupied π orbitals to virtual π(?) orbitals. The same series of transitions has been studied previously by high-level ab initio methods. We compare here the performance of SCF-CV(∞)-DFT to that of time dependent density functional theory (TD-DFT), CV(n)-DFT and ΔSCF-DFT, with the ab initio results as a benchmark standard. It is finally demonstrated how adiabatic TD-DFT and ΔSCF-DFT are related through different approximations to SCF-CV(∞)-DFT. 相似文献
83.
We report the implementation of a method by which to calculate Verdet constants for molecules. The method is based on gauge-including atomic orbitals (GIAOs) and density functional theory. Calculations based on this method afford magneto-optical rotations of the right magnitude for the molecules H2, N2, CO, HF, CH4, C2H2, H2O, and CS2. The results are in satisfactory agreement with experiment. We investigate the dependency of the results on the gauge origin if GIAOs are not chosen, the convergence of the results with the size of the basis set for AOs and GIAOs, and for H2O and CS2 a comparison of gas-phase and liquid phase values. For the small molecules studied here, large polarized basis sets with diffuse functions are required to obtain well converged results. The use of an asymptotically correct Kohn-Sham potential is advantageous. 相似文献
84.
Studies of Benzothiazole and Benzoselenazole Squaraines as Fluorescent Probes for Albumins Detection
Volkova KD Kovalska VB Losytskyy MY Bento A Reis LV Santos PF Almeida P Yarmoluk SM 《Journal of fluorescence》2008,18(5):877-882
Series of squaraine benzothiazole and benzoselenazole dyes were studied as possible fluorescent probes for the detection of
proteins, particularly albumins. It was shown that majority of the studied squaraines give significant fluorescent response
on the human serum albumin (HSA) and bovine serum albumin presence. For squaraine dyes with N-hexyl pendent groups (P-1, P-2, P-3, P-5) about 100−540-fold fluorescence intensity increase upon albumins addition was observed.
At the same time in presence of other proteins, namely insulin, avidin from hen egg white, immunoglobulin G (IgG), carbonic
anhydrase fluorescence enhancement values were considerably lower —up to 43 times in IgG presence. It was noted that generally,
squaraines with long N-hexyl pendent groups demonstrate higher emission increase values upon proteins addition comparing with their analogues with
short N-ethyl tails. It was shown that fluorescence intensity enhancement for benzothiazole squaraine dye P-3, relates linearly to
the HSA concentration over the wide range—from 0.2 to 500 μg/ml. Together with noticeable selectivity of this dye to albumins,
existence of wide dynamic range gives possibility to propose P-3 dye as probe for HSA quantification. 相似文献
85.
ABSTRACTThe influence of non-adiabatic effects on the ro-vibrational bound states of H+ 3 has been investigated using geometry-dependent reduced masses and only one single potential energy surface. The used potentials (BO electronic energy, adiabatic corrections and relativistic contributions) are based on explicitly correlated wavefunctions. For the first time, several different fully geometry-dependent reduced mass surfaces in three dimensions have been incorporated for the vibrational and rotational contributions. 相似文献
86.
A time-dependent density functional theory (TDDFT) formalism with damping for the calculation of the magnetic optical rotatory dispersion and magnetic circular dichroism (MCD) from the complex Verdet constant is presented. For a justification of such an approach, we have derived the TDDFT analog of the sum-over-states formula for the Verdet constant. The results of the MCD calculations by this method for ethylene, furan, thiophene, selenophene, tellurophene, and pyrrole are in good agreement with our previous theoretical sum-over-states MCD spectra. For the pi-->pi(*) transition of propene, we have obtained a positive Faraday B term. It is located between the two negative B terms. This finding is in agreement with experiment in the range of 6-8 eV. 相似文献
87.
Volkova KD Kovalska VB Losytskyy MY Fal KO Derevyanko NO Slominskii YL Tolmachov OI Yarmoluk SM 《Journal of fluorescence》2011,21(2):775-784
In present paper series of trimethine cyanines modified in 5,5′- or 6,6′- position with hydroxy- or methoxy- substituents
is studied for their ability to interact selectively with fibrillar formations. Processes of dye aggregation that accompany
this interaction were also investigated. Meso-methyl trimethynecyanines with 5,5′- methoxy (7519) and hydroxy (7515) substituents
strongly (up to 40 times) increase fluorescence intensity in the presence of fibrillar insulin, and also give noticeable fluorescent
response on the presence of various aggregated proteins (lysozyme, β-lactoglobulin, α-synuclein A53T). 7519 and 7515 dyes
can be used for fluorometric detection of fibrillar insulin at concentrations of approximately 1.5–120 microg/ml. For meso-ethyl
substituted dye 7514 the ability to form H- and J-aggregates upon interaction with insulin fibrils was suggested. The model
of the H- and J-aggregate packing in the protein fibrillar structure has been proposed. 相似文献
88.
Vladyslava B. Kovalska Mykhaylo Yu. Losytskyy Sergiy M. Yarmoluk Irit Lubitz Alexander B. Kotlyar 《Journal of fluorescence》2011,21(1):223-230
Two of earlier reported dsDNA sensitive cyanine dyes??monomethine Cyan 40 and meso-substituted trimethine Cyan 2 were studied for their ability to interact with non-canonical DNA conformations. These dyes were characterized by spectral-luminescent methods in the presence of G-quadruplex, triplex and dsDNA motifs. We have demonstrated that Cyan 2 binds strongly and preferentially to triple- and quadruple-stranded DNA forms that results in a strong enhancement of the dye fluorescence, as compared to dsDNA, while Cyan 40 form fluorescent complexes preferentially only with the triplex form. Highly fluorescent complexes of Cyan 2 with DNA triplexes and G-quadruplexes and Cyan 40 with DNA triplexes are very stable and do not dissociate during gel electrophoresis, leading to preferential staining of the above DNA forms in gels. The data presented point to the intercalation mechanism of the Cyan 2 binding to G4-DNA, while the complexes of Cyan 40 and Cyan 2 with triplex DNA are believed to be formed via groove binding mode. The Cyan dyes can provide a highly sensitive method for detection and quantification of non-canonical structures in genome. 相似文献
89.
Mykhaylo V. Vovk Volodymyr A. Sukach Volodymyr V. Pyrozhenko Andriy V. Bol'but 《Heteroatom Chemistry》2006,17(2):104-111
By the reaction of 6-aryl(alkyl)amino-5-cyano-2,3-dihydro-1,3-thiazin-4(10)-ones with α-halogenoketones in the presence of triethylamine, 2,3-dihydrothieno[2,3-d]pyrimidin-4(1H)-ones have been synthesized and their acid-catalyzed recyclization to 2,3-dihydrothieno[3,4-d]pyrimidin-4(1H)-ones has been found and studied. © 2006 Wiley Periodicals, Inc. Heteroatom Chem 17:104–111, 2006; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/hc.20181 相似文献
90.