Search results for "Computation"
showing 10 items of 7362 documents
Density Functional Theory Investigation on the Nucleation and Growth of Small Palladium Clusters on a Hyper-Cross-Linked Polystyrene Matrix
2014
Density functional theory calculations were employed to investigate the nucleation and growth of small palladium clusters, up to Pd9, into a microcavity of the porous hyper-cross-linked polystyrene (HPS). The geometries and the electronic structures of the palladium clusters inside the HPS cavity, following the one-by-one atom addition, are affected by a counterbalance between the Pd–phenyl (Pd−Φ) and Pd–Pd interactions. The analysis performed on energetics, cavity distortions, and cluster geometries indeed suggest that the cluster growth is dominated by the Pd−Φ interactions up to the formation of Pd4 aggregates, whereas the metal–metal interactions actually rule the growth of the larger c…
On Language Adequacy
2015
Abstract The paper concentrates on the problem of adequate reflection of fragments of reality via expressions of language and inter-subjective knowledge about these fragments, called here, in brief, language adequacy. This problem is formulated in several aspects, the most general one being: the compatibility of the language syntax with its bi-level semantics: intensional and extensional. In this paper, various aspects of language adequacy find their logical explication on the ground of the formal-logical theory of syntax T of any categorial language L generated by the so-called classical categorial grammar, and also on the ground of its extension to the bi-level, intensional and ex- tensio…
Information Decomposition in Bivariate Systems: Theory and Application to Cardiorespiratory Dynamics
2015
In the framework of information dynamics, the temporal evolution of coupled systems can be studied by decomposing the predictive information about an assigned target system into amounts quantifying the information stored inside the system and the information transferred to it. While information storage and transfer are computed through the known self-entropy (SE) and transfer entropy (TE), an alternative decomposition evidences the so-called cross entropy (CE) and conditional SE (cSE), quantifying the cross information and internal information of the target system, respectively. This study presents a thorough evaluation of SE, TE, CE and cSE as quantities related to the causal statistical s…
Theoretical study of nitrogen heterocyclics. IV. Molecular diagrams and carcinogenic activity of some naphthindoles
2010
Molecular-orbital calculations of structural static parameters (bond orders, π-electron densities and free valences) and dynamic indices (atom, ortho- and para-localization energies) are presented for a number of naphthindoles. The results are used to predict the chemical properties of the molecules. We have made a comparison of the carcinogenic inactivity and the static and dynamic complex indices used to characterize the K region in some benzindoles and these naphthindoles.
Theoretical evaluation of structures and energetics involved in the hydrogenation of hydrocarbons on palladium surfaces
2001
Abstract Quantum mechanical calculations were employed to deepen information about the basic properties of the mechanism occurring in the palladium catalytic hydrogenation involving surface hydrogen species of unsaturated hydrocarbons. Activation energy values of elementary events implicated in the whole reaction were computed by potential energy surface analyses, to determine the corresponding occurrence probabilities of the same events. Different surface hydrogen species were pointed out and their relevance in the overall surface process was discussed together with their geometrical and chemical characteristics.
Relationship between Electron Affinity and Half-Wave Reduction Potential: A Theoretical Study on Cyclic Electron-Acceptor Compounds.
2016
A high-level ab initio protocol to compute accurate electron affinities and half-wave reduction potentials is presented and applied for a series of electron-acceptor compounds with potential interest in organic electronics and redox flow batteries. The comprehensive comparison between the theoretical and experimental electron affinities not only proves the reliability of the theoretical G3(MP2) approach employed but also calls into question certain experimental measurements, which need to be revised. By using the thermodynamic cycle for the one-electron attachment reaction A+e- →A- , theoretical estimates for the first half-wave reduction potential have been computed along the series of ele…
Theoretical study of the regio- and stereoselectivity of the intramolecular Povarov reactions yielding 5H-chromeno[2,3-c] acridine derivatives
2016
The intramolecular Povarov (IMP) reactions involved in the synthesis of 5H-chromeno[2,3-c] acridine derivatives [Tetrahedron Lett., 2010, 51, 3071–3074] have been studied using density functional theory (DFT) methods. The studied IMP reaction is a domino process that comprises two consecutive reactions: (i) a BF3 Lewis acid catalysed intramolecular aza-Diels–Alder (IMADA) reaction of an alkene tethered chromene imine (ATCI) giving a formal [4 + 2] cycloadduct, and (ii) a 1,3-hydrogen shift yielding the final chromeno product. The possible regio-(fused/bridged) and stereo-(cis/trans) isomeric channels associated with the IMADA reaction were thoroughly investigated and analysed. The activatio…
Reaction of LiArMe6 (ArMe6= C6H3-2,6-(C6H2-2,4,6-Me3)2) with indium(I)chloride yields three m-terphenyl stabilized mixed-valent organoindium subhalid…
2016
Abstract Indium(I)chloride reacts with LiAr Me 6 ( Ar Me 6 = C6H3-2,6-(C6H2-2,4,6-Me3)2) in THF to give three new mixed-valent organoindium subhalides. While the 1:1 reaction of InCl with LiAr Me 6 yields the known metal-rich cluster In8( Ar Me 6 )4 (1), the use of freshly prepared LiAr Me 6 led to incorporation of iodide, derived from the synthesis of LiAr Me 6 , into the structures, to afford In4( Ar Me 6 )4I2 (2) along with minor amounts of In3( Ar Me 6 )3I2 (3). When the same reaction was performed in 4:3 stoichiometry, the mixed-halide compound In3( Ar Me 6 )3ClI (4) was obtained. Further increasing the chloride:aryl ligand ratio resulted in the formation of the known mixed-halide spe…
Lithium Cation-Catalyzed Benzene Diels-Alder Reaction: Insights on the Molecular Mechanism Within the Molecular Electron Density Theory.
2020
The lithium cation Li+-catalyzed Diels-Alder (DA) reactions of benzene toward a series of acetylenes of improved nucleophilicity can be described within the context of the molecular electron density theory (MEDT) at the ωB97XD/6-311G(d,p) level. Conceptual density functional theory indices characterize the crown ether solvated complex benzene-lithium Bz-Li-Cro as a superelectrophile. Coordination of a lithium cation to benzene does not change substantially the electron localization function electronic structure of benzene. The DA reaction of Bz-Li-Cro with acetylene shows a reduction of the energy of activation of 6.9 kcal·mol-1, which is not sufficient for the reaction to take place, thus …