Advanced Theory and Simulations最新文献

Corannulene, C₂₀H₁₀, experience a bowl-to-bowl inversion through planar conformation. The replacement of the N4-kernel in metalloporphyrins (MN4) to P4, leading to metallophosphaporphyrins (MP4), introduces steric effects resulting a bowl-like MP4 counterpart. Here, we explore the driving terms in determining the bowl-shape in the first transition metal series from Sc to Zn (MP4), by using Density Functional Theory (DFT) methods, and the related variation of the particular π-hole and UV–vis characteristics in relation to parent metalloporphyrins. Our results reveal that the variation of flat to bowl structure for the MP4 series for the Sc─Mn metals, is driven mainly by the release in the Pauli repulsion, whereas for the Fe─Zn, is provided by the main contribution from the electrostatic stabilization achieved in the bowl-like MP4 structure. Particularly for NiP4 and CoP4, a bowl-to-bowl inversion is expected to be favorable. The π-hole capabilities are largely enhanced in the bowl MP4 structure for Sc, Ti, V, Cr, and Mn, in comparison to their MP4 parents. In contrast, for the related CoP4, NiP4, CuP4, and ZnP4, species denote a more electron-rich π-hole site. These observations denote that the use of a more sterically demanding P4-coordination site serves as a plausible design strategy to expand the characteristics of metalloporphyrins.

Remarkable properties of 2D silicene have made it a potential future nanoscale interconnect, required for next-generation electronic devices. In this present work, a comprehensive density-functional theory (DFT) and non-equilibrium Green's function (NEGF) approaches have been implemented to analyse the the impact of P-type (Boron, Aluminium) and N-type (Nitrogen, Phosphorus) doping in zigzag silicene nanoribbons (ZSiNRs), focusing on their structural stability, electronic characteristics, and transport properties along with dynamical parameters and device-level metrics, including signal delay, power–delay product, and maximum frequency of operation (MFOO). Out of six possible doping sites, edge-site doping is found to be energetically favorable, with N-doped ZSiNRs exhibiting the highest thermodynamic stability. Electronic structure analyses show enhanced metallicity upon doping, while transport calculations indicate distinct doping-dependent behavior. B-doped ZSiNRs exhibit the lowest delay and MFOO, suggesting reduced signal delay, whereas N-doped ZSiNRs demonstrate improved thermodynamic stability with linear current–voltage (I–V) characteristic, low delay, and high MFOO, making them potential candidates for the interconnect applications.

The Monte Carlo (MC) simulation is an effective technique for capturing the dynamic evolution of Particulate-Filled Systems (PFS), as it allows detailed tracking of individual droplet histories. This flexible method is widely applied across many fields and, owing to its simple implementation and robust performance, often has no suitable alternative. However, the long computational time, especially when a large number of droplets is simulated, remains a significant drawback. The primary aim of this study is to address this limitation by introducing a novel strategy for incorporating large droplet populations into MC simulations, thereby reducing the time required to model extensive systems. A new mathematical procedure is combined with a time-increment MC model to develop a hybrid framework, referred to as the Combinatorial Approach (CAx), which enables the use of sufficiently large initial sample populations to predict the dynamic evolution of particle size distributions in suspension polymerization. The key feature of CAx is the combination of multiple distinct simulation runs into a single vector, providing higher precision than conventional MC simulations. This framework significantly reduces computational time while maintaining high accuracy in the predicted results.

Barium(II) (Ba[II]) ion activation considerably increases quartz recovery, reaching up to 99.85%, as shown by micro-flotation studies. Ba(II) ions preferentially adsorb onto the quartz surface, creating active sites through electrostatic interactions that facilitate sodium oleate (NaOL) adsorption, as demonstrated by zeta potential measurements. Chemical adsorption is confirmed by Fourier-transform infrared spectroscopy and X-ray photoelectron spectroscopy. Electronic density difference and density of states studies reveal strong electron transport between Ba and O, forming persistent chemical bonds. By combining chemical bonding and physical adsorption, Ba(II) ions improve NaOL adsorption on the quartz surface, offering a theoretical foundation for flotation.

The structure of three-step quantum well is receiving attention to improve the response of nonlinear optical coefficients. Here we investigate second harmonic generation produced in an asymmetric three-step quantum well by exploiting both structural parameters and external fields for maximizing the value of response aiming at elucidating the value of parameter regulation. Regarding structural parameters, variations in central barrier thickness and well width induce multiple resonance peaks in the second-order nonlinear susceptibility, attributed to quantum confinement effects and energy level spacing modifications. Electric fields induce Stark shifts that alter wavefunction overlap and dipole matrix elements, while magnetic fields introduce Landau quantization that interacts with structural asymmetry to generate additional nonlinear polarization. The SHG induced by asymmetric three-step quantum well is theoretically studied for the first time, demonstrating that the resonance peak of the second harmonic coefficient changes significantly by adjusting the parameters within a certain range. Our findings can be of interest in parameter design and experimental applications of optoelectronic devices for the selection of the more appropriate nonlinear optical configuration.

Light-driven chlorine evolution reaction (CER), with suitable non-noble metal photocatalysts, is an effective means to replace electrocatalytic CER and alleviate energy crises. Herein, the photocatalytic CER performance of Cu-BTC, a metal organic framework doped with transition metals (TM), is assessed by density functional theory calculations. The results reveal that as the d-electron filling of TM increases, the free energy of chlorine adsorption approaches zero, wherein pristine Cu-BTC possesses thermodynamic ΔG_*Cl close to zero, and CuTM-BTC with TM of Ni, Pd, and Pt exhibit |ΔG_*Cl| less than 0.3 eV, reflecting excellent CER activity. Especially, the bimetallic active sites of CuNi-BTC and CuPd-BTC exhibit enormous potentials. Furthermore, the candidates offer the suitable highest occupied molecular orbitals (HOMO), being more negative than the oxidation potential of Cl⁻/Cl₂, which is beneficial for the excitation of charge carriers. The electronic structure analysis demonstrates that a good linear relationship is established between the CER overpotentials and the energy levels of HOMO. In the regard, this work sheds lights on the modification of photocatalytic activity via regulation of the energy levels of HOMO.