Description of noncovalent interactions involving π-system with high precision: An assessment of RPA,MP2, and DFT-D methods

Efficient approaches with high precision are essential for understanding the formation and stability of noncovalent interaction complexes. Here, 21 noncovalent interaction complexes involving π-system are selected and grouped in three subsets according to ETS–NOCV method: dispersion-dominated, electrostatic-dominated, and mixed. We mainly focus on examining the performance of random-phase approximation (RPA) on these π systems. The tested RPA-based method includes standard RPA and its variants including the related single excitations (SEs), renormalized single excitations (rSEs), second-order screened exchange (SOSEX), and the renormalized second-order perturbation theory (rPT2). The routine second-order Møller–Plesset perturbation theory (MP2) and three popular DFT-D functionals (M06-2X-D3, ωB97XD, and PBE-D3(BJ)) are also assessed for comparison. In this work, besides the calculation of interaction energies at Dunning-type aug-cc-pVDZ and aug-cc-pVTZ basis set, we also present a larger database of interaction energies calculated using MP2 and RPA methods with Dunning-type aug-cc-pVQZ basis set. An accurate CCSD(T)/CBS scheme is used to provide benchmark database. In addition to the high-level results, we also provide potential energy surfaces (PES) of different interaction type. Among all the tested methods, MP2 has a satisfactory performance on electrostatic-dominated and mixed-type systems, except for dispersion-dominated systems. DFT-D functionals, especially ωB97XD functional, has a balanced performance across all the tested systems. Importantly, for RPA-based methods, the calculation accuracy can be dramatically improved by taking into account SE or exchange effects, especially in the mixed complexes. We conclude that rPT2 among all the test RPA-based methods gives an overall satisfactory performance across different interaction types. © 2019 Wiley Periodicals, Inc.     

Near-threshold η production in the <Emphasis Type="Italic">pd</Emphasis>→<Emphasis Type="Italic">pd</Emphasis>η reaction

The total cross section of the pd→pdη reaction has been measured at two energies near threshold by detecting the final proton and deuteron in a magnetic spectrometer. The values are somewhat larger than expected on the basis of two simple theoretical estimates. Received: 23 March 2000     

One- and two-neutron transfer reactions on 12C with the weakly bound 6He projectile

Using the framework of the coupled reaction channels (CRC) the one- and two-neutron transfer process initiated by the weakly bound nucleus ⁶He on ¹²C at an energy of E _L = 5.9 MeV is studied. The absolute cross-sections for a few states in ¹⁴C are well reproduced within a factor 2 in second order, using microscopic wave functions of ⁶He and ¹²C. Only a small dependence of the cross-section on details of the ⁶He wave function is observed. Good fits to the data are obtained in a calculation with full coupling (25 iterations) with renormalised optical potential parameters and spectroscopic amplitudes of ⁶He. Received: 13 June 2000 / Accepted: 24 July 2000     

The evolution of steep fronts in non-fickian polymer-penetrant systems

We adapt a recently proposed model for non-Fickian diffusion of penetrants into polymers and use it to study a drug-delivery problem. The model modified Fick's diffusion equation by the addition of stress-induced flux. A stress evolution equation incorporating aspects of the Maxwell and Kelvin-Voigt viscoelastic stress models completes the model. The relaxation time in the polymer is taken as a function of the penetrant concentration. The system is studied under the assumption that the diffusivity is large. Singular perturbation techniques are used to show that the concentration and stress evolve diffusively for small time, but exhibit steep fronts in a narrow region within the domain for larger time. These predictions are verified numerically for specified parameter values. Finally, the equations are studied in the steady state and are found to predict the evolution of shocks.     

基于熵权灰色关联分析的群体性突发事件预警模型

群体性突发事件是当前我国社会危机的一个突出问题,迫切需要进行有效地监测与预警.针对江门的社会、经济、文化特点,设计了一套群体性突发事件预警指标体系.引入信息熵理论,采用熵值法来确定指标权重,建立了基于熵权和灰色关联度的群体性突发事件预警模型.用上述模型对江门市进行实证研究,表明江门市2005年-2008年间除2006年处于中险警级外,其余年份都处于轻险警级.最后,根据实证分析结果,提出了政策建议.     

Auxiliary principle and iterative algorithm for a new system of generalized mixed equilibrium problems in Banach spaces

In this paper, we study a new system of generalized mixed equilibrium problems involving skew-symmetric bifunctions (SGMEP) in reflexive Banach spaces. A system of auxiliary mixed equilibrium problems (SAMEP) for solving the SGMEP is introduced and the existence and uniqueness of the solutions of the SAMEP is first proved. Next, by using the auxiliary principle technique, a new iterative algorithm to compute the approximate solutions of the SGMEP is suggested and analyzed. Finally, the strong convergence of the iterative sequences generated by the algorithm is also proved under quite mild conditions. These results improve, unify and generalize some known results in recent literature.     

Cyanosilylation of Prochiral Ketones Catalyzed by Lanthanide Complexes

A new series of silylene‐bridged rare‐earth complexes involving fluorenyl are shown to be the very efficient Lewis acid catalysts, giving some cyano trimethylsilyl ethers of ketones in >99% yields.     

Controllability of Hilfer Fractional Differential Systems with Non-Dense Domain

In this paper, some exact controllability results are investigated for an integral solution of a non-densely defined abstract fractional differential system involving Hilfer fractional derivative. We tend to implement semigroup theory, fractional calculus, and measure of noncompactness to obtain the main results by fixed point technique. Finally, an application is given to illustrate the obtained results.     

Stabilization of catalytically active gold species in Fe-modified zeolites

The influence of iron additive on redox, electronic and catalytic properties of gold incorporated into zeolite catalysts has been studied by means of TEM, XPS, XRD, TPR, ICP and AES. The interaction of gold with iron modifier was observed in Y-zeolites and mordenites with different cations and method of Fe incorporation (impregnation or ion exchange). This interaction leads to mutual influence on redox properties of Fe and Au ionic species and facilitates their reduction. Limited diffusion of Au precursor after Fe species deposition in narrow mordenite channels does not permit to incorporate Au in adequate concentration, while in large super-cage of Y-zeolites this limitation is absent. The structure of Y-zeolites favors formation of active gold species. Catalytic tests in CO oxidation show that Fe additive stabilizes the gold active species active at low-temperature (partly charged clusters) and makes them insensitive to redox treatments.