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2D materials are increasingly being investigated for their nonvolatile switching properties as a step toward downscaling of core electronic elements. Here, the interplay between electrochemically active silver (Ag) cations and layered indium selenide (InSe), a 2D metal monochalcogenide, is investigated to demonstrate a nonvolatile switching device. Detailed microscopic characterization supported with density functional theory calculations reveals cationic filamentary‐based nonvolatile switching mechanism of γ‐InSe in a crossplanar architecture. This is electrically driven by diffusion of Ag ions through the layered InSe stack. The InSe‐based memory cells exhibit a switching ratio of ≈103 and a memory retention of >105 s. This work opens new opportunities to enhance resistive switching performances of 2D materials for next‐generation information storage and brain inspired computation using active metal diffusion. [ABSTRACT FROM AUTHOR]

Catalytic solvent regeneration has attracted broad interest owing to its potential to reduce energy consumption in CO2 separation, enabling industry to achieve emission reduction targets of the Paris Climate Accord. Despite recent advances, the development of engineered acidic nanocatalysts with unique characteristics remains a challenge. Herein, we establish a strategy to tailor the physicochemical properties of metal-organic frameworks (MOFs) for the synthesis of water-dispersible core-shell nanocatalysts with ease of use. We demonstrate that functionalized nanoclusters (Fe3O4-COOH) effectively induce missing-linker deficiencies and fabricate mesoporosity during the self-assembly of MOFs. Superacid sites are created by introducing chelating sulfates on the uncoordinated metal clusters, providing high proton donation capability. The obtained nanomaterials drastically reduce the energy consumption of CO2 capture by 44.7% using only 0.1 wt.% nanocatalyst, which is a ∽10-fold improvement in efficiency compared to heterogeneous catalysts. This research represents a new avenue for the next generation of advanced nanomaterials in catalytic solvent regeneration. Catalytic solvent regeneration is of interest to reduce energy consumption in CO2 separation, however, the development of engineered nanocatalysts remains a challenge. Here, a new avenue is presented for the next generation of advanced metal-organic frameworks (MOFs) in energy-efficient CO2 capture. [ABSTRACT FROM AUTHOR]

In this paper we discuss a new simulation method that can be used to predict preferred surface reconstructions of model systems by Molecular Dynamics (MD). The method overcomes the limitations imposed by periodic boundary conditions for finite boundary MD simulations which can normally prevent reconstructions. By simulating only the reconstructed surface layer and by removing the periodic boundary effects and the free energy barriers to reconstruction, the method allows surfaces to reconstruct to a preferred structure. We test the method on three types of surfaces: (i) the Au(100) and Pt(100) hexagonally reconstructed surface, (ii) the Au(111) herringbone surfaces, and (iii) the triangularly reconstructed Ag surface layer on a Pt(111) substrate and find the method readily finds lower surface energy reconstructions as preferred by the potential. [ABSTRACT FROM AUTHOR]

We derive new quantum Monte Carlo (QMC) estimators for the electronic density at the position of a point nucleus using the zero-variance and zero-bias principles. The resulting estimators are highly efficient, and are significantly simpler to implement and use than alternative methods, as they contain no adjustable parameters. In addition, they can be used in both variational and diffusion QMC calculations. Our best estimator is used to calculate the most accurate available estimates of the total electron density at the nucleus for the first-row atoms Li-Ne, the Ar atom, and the diatomic molecules B2, N2, and F2. [ABSTRACT FROM AUTHOR]

We derive efficient quantum Monte Carlo estimators for the anisotropic intracule and extracule densities. These estimators are used in conjunction with an accurate explicitly correlated wave function to investigate the bond-length dependence of electron correlation effects in the ground-state H2 molecule. It is shown that the localized increase in the magnitude of the correlation energy as the bond is stretched is accompanied by highly anisotropic correlation effects. In addition, we find a small long-range part of the Coulomb hole, which is present even at the equilibrium bond length. [ABSTRACT FROM AUTHOR]

An accurate description of electron correlation is essential for the calculation of interaction energies in cases where dispersion energy is a major component, for example, for the rare gas atoms, physisorption on graphite, and graphene-graphene interactions. Such calculations are computationally demanding using supermolecule methods and the energies calculated lack a simple, physical interpretation. Alternatively density functional theories (DFTs) may be used to give an approximate estimate of the correlation energy. However, the physical nature of this DFT estimate of electron correlation energy is not well understood and, in fact, most current DFT methods do not describe dispersion energy at all. Hence, an analysis of the correlation energy contribution to interaction energies where dispersion energy is important is needed. In order to do this we provide an analysis of the correlation energy contribution to the potential energy curves of He2, Ne2, and Ar2 in terms of the Hartree–Fock (HF) interaction term ΔEintHF, a dispersion energy term Edisp and an electron correlation term ΔEintC. ΔEintC includes all other correlation energy effects besides Edisp and is shown to be repulsive, of a similar short range character to, but of smaller magnitude than ΔEintHF. This analysis was used to develop a theoretical model which gives a very good estimate of the potential energy wells for He2, Ne2, Ar2, HeNe, HeAr, and NeAr. [ABSTRACT FROM AUTHOR]

We have simulated the vacuum deposition and subsequent growth of gold nanoparticles on various substrates in order to explore the effects that substrate morphology has on the resultant morphology of gold nanoparticles. The substrates and conditions explored included, the three low index faces, namely, (111), (100), and (110) for both fcc and bcc crystalline substrate structures, including various substrate lattice constants and temperatures. Firstly, we cataloged the major nanoparticle morphologies produced overall. While some substrates were found to produce a mixture of the main nanoparticle morphologies we were successful in identifying certain substrates and temperature conditions for which only Ih, Dh, or certain fcc crystalline nanoparticles can be grown almost exclusively. The substrate characteristics, temperature conditions, and governing growth dynamics are analyzed. We shed light on the balance between substrate influences and vacuum growth tendencies. From observations we can speculate that a substrate alters both the free energy stability of gold nanoparticles and/or the free energy barriers to transformation between certain morphologies. As such we find that substrates are an effective tool in templating the selective growth of desired nanoparticles or surface nanostructures. [ABSTRACT FROM AUTHOR]

A simple method is presented which ensures the electron-nucleus cusp condition is satisfied by the Slater-Jastrow wavefunctions commonly employed in quantum Monte Carlo simulations. The method is applied in variational energy calculations of the neon atom and a selection of molecules using both Gaussian and Slater basis sets. In addition, we discuss the relationship between the electron-nucleus cusps and the variance of forces, and investigate the sensitivity of forces to the quality of the cusps for various diatomic molecules. [ABSTRACT FROM AUTHOR]