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Global diabatic potential energy surfaces (PESs) of CH2+ are constructed using the neural network method with a specific function based on 18 213 ab initio points. The multi-reference configuration interaction method with the aug-cc-pVQZ basis set is adopted to perform the ab initio calculations. The topographical properties of the diabatic PESs are examined in detail. In general, the diabatic PESs provide an accurate quasi-diabatic representation. To validate the diabatic PESs, the dynamics studies of the C+(2P1/2, 3/2) + H2 (v0 = 0, j0 = 0) → H + CH+(X1Σ+) reaction are performed using the time-dependent wave packet method. The reaction probabilities, integral cross sections, differential cross sections, and rate constants are calculated and compared with the experimental and theoretical results. Non-adiabatic dynamics results are in good agreement with experimental data. In addition, the non-adiabatic effect in the C+(2P1/2, 3/2) + H2 reaction is significant due to the non-adiabatic results being obviously larger than adiabatic values. The reasonable non-adiabatic dynamics results indicate that present diabatic PESs can be recommended for any type of dynamics study. [ABSTRACT FROM AUTHOR]

The construction of diabatic potential energy surfaces (PESs) for the SiH2+ system, related to the ground (12A′) and excited states (22A′), has been successfully achieved. This was accomplished by utilizing high-level ab initio energy points, employing a neural network fitting method in conjunction with a specifically designed function. The newly constructed diabatic PESs are carefully examined for dynamics calculations of the Si+(2P1/2, 3/2) + H2 reaction. Through time-dependent quantum wave packet calculations, the reaction probabilities, integral cross sections (ICSs), and differential cross sections (DCSs) of the Si+(2P1/2, 3/2) + H2 reaction were reported. The dynamics results indicate that the total ICS is in excellent agreement with experimental data within the collision energy range studied. The results also indicate that the SiH+ ion is hardly formed via the Si+(2P3/2) + H2 reaction. The results from the DCSs suggest that the "complex-forming" reaction mechanism predominates in the low collision energy region. Conversely, the forward abstraction reaction mechanism is dominant in the high collision energy region. [ABSTRACT FROM AUTHOR]

Understanding the correlation between the fundamental descriptors and catalytic performance is meaningful to guide the design of high‐performance electrochemical catalysts. However, exploring key factors that affect catalytic performance in the vast catalyst space remains challenging for people. Herein, to accurately identify the factors that affect the performance of N2 reduction, we apply interpretable machine learning (ML) to analyze high‐throughput screening results, which is also suited to other surface reactions in catalysis. To expound on the paradigm, 33 promising catalysts are screened from 168 carbon‐supported candidates, specifically single‐atom catalysts (SACs) supported by a BC3 monolayer (TM@VB/C‐Nn = 0–3‐BC3) via high‐throughput screening. Subsequently, the hybrid sampling method and XGBoost model are selected to classify eligible and non‐eligible catalysts. Through feature interpretation using Shapley Additive Explanations (SHAP) analysis, two crucial features, that is, the number of valence electrons (Nv) and nitrogen substitution (Nn), are screened out. Combining SHAP analysis and electronic structure calculations, the synergistic effect between an active center with low valence electron numbers and reasonable C‐N coordination (a medium fraction of nitrogen substitution) can exhibit high catalytic performance. Finally, six superior catalysts with a limiting potential lower than −0.4 V are predicted. Our workflow offers a rational approach to obtaining key information on catalytic performance from high‐throughput screening results to design efficient catalysts that can be applied to other materials and reactions. [ABSTRACT FROM AUTHOR]

Currently, intercalation has become an effective way to modify the fundamental properties of two-dimensional (2D) van der Waals (vdW) materials. Using density functional theory, we systematically investigated the structures and electronic and magnetic properties of bilayer transition metal dichalcogenides (TMDs) intercalated with 3d TM atoms (TM = Sc–Ni), TM@BL_MS2 (M = Mo, V). Our results demonstrate that all the studied TM@BL_MS2s are of high stability, with large binding energies and high diffusion barriers of TM atoms. Interestingly, most TM@BL_MoS2s and TM@BL_VS2s are found to be stable ferromagnets. Among them, TM@BL_MoS2s (TM = Sc, Ti, Fe, Co) are ferromagnetic metals, TM@BL_MoS2 (TM = V, Cr) and TM@BL_VS2 (TM = Sc, V) are ferromagnetic half-metals, and the remaining systems are found to be ferromagnetic semiconductors. Exceptions are found for Ni@BL_MoS2 and Cr@BL_VS2, which are nonmagnetic semiconductors and ferrimagnetic half-metals, respectively. Further investigations reveal that the electromagnetic properties of TM@BL_MoS2 are significantly influenced by the concentration of intercalated TM atoms. Our study demonstrates that TM atom intercalation is an effective approach for manipulating the electromagnetic properties of two-dimensional materials, facilitating their potential applications in spintronic devices. [ABSTRACT FROM AUTHOR]

The valley-polarized quantum anomalous Hall (VP-QAH) materials, which combine valley polarization and the quantum anomalous Hall (QAH) effect, are of both fundamental and technological importance due to their potential applications for nanoscale devices. Here, we explored the stability, magnetic, and topological properties of two-dimensional MnTiX2 (X = F/Cl/Br) monolayers based on first-principles calculations. Our results show that all the structures have robust antiferromagnetic orders with large magnetic anisotropic energies and high transition temperatures (480–670 K). In the absence of spin–orbital coupling (SOC), the MnTiX2 monolayers represent antiferromagnetic quadratic crossing semimetals. In the presence of SOC, the quadratic crossing points of the systems are opened with sizable bandgaps (> 0.5 eV), and they are transformed to be QAH insulators with |C| = 1. Moreover, the MnTiF2 monolayer is found to be a spontaneous VP-QAH semiconductor due to the time reversal symmetry and inversion symmetry being broken. These insights provide an ideal platform for achieving VP-QAH materials for dissipationless transport and quantum computing. [ABSTRACT FROM AUTHOR]

Two-dimensional (2D) polymeric carbon nitride (PCN) materials have drawn broad attention as promising candidates for photocatalytic hydrogen evolution. However, it remains a significant challenge to simultaneously improve the visible light absorption, separation of photogenerated carriers, and activity. Herein, alkali metals doping PCN (e.g., C6N6 and C2N) are systematically investigated based on density functional theory. Different from the conventional notion of doping atoms as active sites, the actual active site is the intrinsic pyridine nitrogen surrounding the alkali metal. Compared to the change of Gibbs free energy value of −0.45 eV (−0.60 eV) for pristine C6N6 (C2N), Li or Cs doped PCN decreases to −0.03 eV (−0.10 eV) or 0.06 eV (−0.11 eV), respectively, benefitting from the adjustment of the 3p electronic state occupation for N atoms by charges transfer from alkali metal. Meanwhile, Li or Cs doping not only broadens the absorption of visible light by narrowing the band edge position but also promotes the separation of photogenerated electrons and holes by regulating their spatial separation, which is further confirmed by significant photocurrents for Li or Cs doped PCN based on nonequilibrium Green's function simulation. Our work could provide interesting insights into the mechanistic understanding and the highly efficient design of PCN materials in photocatalysis. [ABSTRACT FROM AUTHOR]

Two-dimensional transition metal borocarbides with intrinsic magnetism have garnered significant research attention due to their potential applications in spintronics. Using density functional theory calculations, we designed a type of transition metal borocarbides with two distinct configurations, TMBC-Is and TMBC-IIs (TM = V–Co), and explored their electronic and magnetic properties. Our results demonstrate that all the studied systems exhibit both thermal and kinetic stability. Notably, four systems of MnBC-I/MnBC-II and FeBC-I/FeBC-II are robust ferromagnetic (FM) half metals (HMs) with Curie temperatures of 145, 180, 108, and 315 K. Expect FeBC-II monolayer, FM to antiferromagnetic transition occurs for three other FM HMs under 8%–10% compressive strains, while FM HM to FM semiconductor transition is found for MnBC-II monolayer under 8% tensile strain. These findings provide a promising way to design two-dimensional FM HMs, which hold potential applications in spintronics. [ABSTRACT FROM AUTHOR]

Developing proper semiconductor photocatalysts is urgently needed to solve energy and environmental crises. Especially, photocatalysts for water splitting with a Z-scheme mechanism are desirable materials. Herein, a two-dimensional VTe-MoTe2/GeN heterostructure (VTe-HS), including single Te vacancy, is theoretically proved to function as a direct Z-scheme photocatalyst with the wide light-harvesting range, the effective spatial separation for carriers, and the high catalytic activity for water splitting. An enhanced optical absorption coefficient of 105 cm−1 is observed and the absorption edge (∼1.0 eV) is red-shifted into the infrared light region. Separating photogenerated electron–hole pairs enhances the photocatalytic efficiency due to the staggered band alignment. Interlayer charge migration of about 0.154 electrons induces an intrinsic built-in electric field in the heterostructure, allowing forming the Z-scheme mechanism with a reduction potential of –4.01 eV and an oxidation potential of –7.13 eV. Gibbs free energies confirm that water redox reactions can proceed spontaneously under sunshine. Moreover, the Heyrovsky reaction is kinetically more favorable than the Tafel reaction because of a little energy barrier (0.071 eV). These features show that the VTe-HS is a desirable water-splitting photocatalyst, providing a valuable clue to constructing high-efficiency photocatalysts. [ABSTRACT FROM AUTHOR]

Mn2+-doped perovskites nanocrystals (NCs) have already been extensively studied in fascinating optical, electronic, and magnetic properties. Such interesting traits make them paid considerable attention in light emitting diodes, solar cells, etc. However, the underlying thermal and photophysical processes governing the overall charge carrier dynamics in Mn-doped NCs are far from clear. Herein, trap concentration and thermalization-dependent optical properties of Mn–Cu co-doped CsPbCl3 NCs were investigated via using steady-state, time-resolved PL spectra, variable-temperature PL spectra, and ultrafast transient absorption spectra. The combined experimental and theoretical studies reveal that Cu2+, as an effective hole trap, can trap the holes from Mn2+ and emit the holes to Mn2+ level at lighter and higher doping, respectively. Moreover, this hole trap is highly thermally sensitive, which is responsible for the abnormal thermal effect of Mn2+ emission with increasing temperature. These findings demonstrate an approach of charge regulation through ion doping, which is meaningful for fabricating efficient photoelectric materials and devices. [ABSTRACT FROM AUTHOR]

Exploring intrinsic two-dimensional (2D) ferromagnetic (FM) materials with high Curie temperatures (TC) and large magnetic anisotropy energies (MAE) is one of the effective solutions to develop materials for high-performance spintronic applications. Using density functional theory calculations and high-throughput computations, we predict an intrinsic bimetallic FM monolayer, CrAuTe2, which has a large MAE and high TC. The results show that the value of the MAE can reach about 1.5 meV per Cr, and Monte Carlo simulations show that the TC of monolayer CrAuTe2 is about 840 K. Further analysis indicates that the joint effects of spin–orbit coupling (SOC) interaction and magnetic dipole–dipole interaction result in high in-plane magnetic anisotropy. In addition, this monolayer has good dynamic, thermal, and mechanical stabilities, which were confirmed by ab initio molecular dynamics simulations, phonon spectra, and elastic constants, respectively. In order to propose a practical synthesis approach, we built a CrAuTe2/graphene van der Waals heterostructure, and found that the heterostructure does not affect the magnetic properties of monolayer CrAuTe2. These findings appear promising for the future applications in nano-spintronics. [ABSTRACT FROM AUTHOR]

Spin–orbit torque provides an efficient way to achieve switching of perpendicular magnetization, which is essential for designing energy-efficient spintronic devices. An in-plane antidamping torque combined with an out-of-plane antidamping torque can often deterministically switch perpendicular magnetization without an external magnetic field. Encouragingly, field-free perpendicular magnetization switching of a two-dimensional (2D) material WTe2/ferromagnet bilayer has been reported recently, but the working temperature (< 200 K) is quite below room temperature. Here, we demonstrate field-free perpendicular magnetization switching in the Pt/Co/Pt/WTe2 multilayer films at room temperature, which is mainly attributed to the out-of-plane antidamping torque originating from the WTe2 layer. In addition, current-induced perpendicular magnetization switching at zero magnetic field is also accomplished in the [Co/Pt]2/WTe2 multilayer film with a very large perpendicular magnetic anisotropic field (∼13 600 Oe), which is very useful for practical applications. This work offers a potential way to develop spintronic devices based on 2D materials at room temperature. [ABSTRACT FROM AUTHOR]

The non-adiabatic dynamical calculations of the K(4s2S) + H2(v 0 = 1, 2, j 0 = 0) reaction are carried out using the time-dependent wave packet method. The non-adiabatic dynamics results, such as reaction probabilities and integral cross sections, are calculated and compared with previous adiabatic values. The adiabatic values are several tens of times larger than those of the non-adiabatic results. The non-adiabatic effect becomes stronger with the increase in the number of excited vibrational states. In addition, the excitation of the vibrational states of H2 can increase the reaction probability of the reaction channel. However, the KH product is still barely formed through the K(4s2S) + H2 reaction, even if the H2 molecule is excited to a high vibrational excited state, which also leads to the opposite conclusion from the adiabatic results. The forward-biased differential cross sections indicate that a direct stripping mechanism plays a dominant role in the reaction. [ABSTRACT FROM AUTHOR]

The electronic structure and optical properties of van der Waals heterostructures with different layers of MoS2 and VS2 stacks were studied by first-principles calculations based on density functional theory. The stability of two heterojunctions at room temperature was verified through ab initio molecular dynamics. In addition, both heterojunctions exhibit p-type Schottky contact. But compared to the heterojunction composed of monolayer MoS2, the barrier height in the heterojunction formed by the stacking of bilayer MoS2 and VS2 significantly decreases from 0. 36 eV to 0. 08 eV, effectively forming a low contact resistance and reducing the energy loss of carrier transport. The calculation of the light absorption spectrum indicates that the heterojunction composed of bilayer MoS2 has higher absorption peaks. The research results provide a theoretical basis for the design of heterojunctions based on MoS2 and their applications in high-performance optoelectronic devices. [ABSTRACT FROM AUTHOR]