Theoretical Study on the Spectroscopic Properties and Line Intensities of the O Cation.

O cation, as one of the major gas components in the near space environment, has attracted significant attention due to its spectroscopic properties. In this study, we systematically investigate the spectroscopic properties of the O cation using ab initio methods. The potential energy curves and transition dipole moments of O were obtained using the icMRCI + Q method combined with the ACV5Z-DK basis set.

Rate coefficients for C and O2 reactive collisions relevant to interstellar clouds from QCT and machine learning.

The chemical reactions between certain interstellar molecules are exothermic in nature and barrierless in the entrance channel, allowing these reactions to occur rapidly even at low astronomical temperatures, e.g., C and O2 interaction.

Exhaustive State-to-State Cross Sections and Rate Coefficients for Inelastic N-N Collisions using QCT Combined with Neural Network Models.

Using the quasi-classical trajectory method, we systematically studied the state-to-state vibrational relaxation process of N() + N() collisions over a wide temperature range (5000-30,000 K). Different temperature dependencies of the single- and multiquantum VV and VT events in various (,) collisions are captured, with the dominant channel being related to the initial vibrational energy levels ( = 50). At a specified relative translational energy, there is a monotonic relationship of the VT cross sections with the vibrational energy level, particularly in high-energy collisions.

Strain and Electric Field Engineering of G-ZnO/SnXY (X, Y = S, Se) S-Scheme Heterostructures for Photocatalyst and Electronic Device Applications: A Hybrid DFT Calculation.

Using hybrid density functional theory calculations, we systematically study the biaxial strain and electric field modulated electronic properties of g-ZnO/SnS, g-ZnO/SnSe, and g-ZnO/SnSSe S-scheme van der Waals heterostructures (vdWHs). g-ZnO/SnS and g-ZnO/SnSSe are found to be promising photocatalysts for water splitting with high solar-to-hydrogen efficiencies, even under acidic, alkaline, and high-stress conditions. The strain effect on the bandgaps of g-ZnO/SnXY is explained in detail according to the correlation between geometry structure and orbital hybridization of SnXY, which could help understand the strain-induced band structure evolutions in other SnXY (X, Y = S, Se)-based vdWHs.

State-to-state dynamics and machine learning predictions of inelastic and reactive O(3P) + CO(1∑+) collisions relevant to hypersonic flows.

The state-to-state (STS) inelastic energy transfer and O-atom exchange reaction between O and CO(v), as two fundamental processes in non-equilibrium air flow around spacecraft entering Mars' atmosphere, yield the same products and both make significant contributions to the O + CO(v) → O + CO(v') collisions. The inelastic energy transfer competes with the O-atom exchange reaction. The detailed reaction mechanisms of these two elementary processes and their specific contributions to the CO relaxation process are still unclear.

Ideal two-dimensional quantum spin Hall insulators MgATe (A = Ga, In) with Rashba spin splitting and tunable properties.

For decades, topological insulators have played a pivotal role in fundamental condensed-matter physics owing to their distinctive edge states and electronic properties. Here, based on in-depth first-principles calculations, we investigate the MgATe (A = Ga, In) structures belonging to the MAZ 2D material family. Among them, the topological insulator MgGaInTe exhibits band inversion and a sizeable bandgap of up to 60.

Theoretical Study on the Spectroscopic Properties and Line Intensity of Silicon Monosulfide Cation.

The SiS cation is considered a potential astromolecule, yet there is limited documentation regarding its spectroscopic properties and spectral line intensities. In this paper, the potential energy curves, dipole moments, and transition dipole moments of the SiS cation are calculated using the icMRCI + Q method. By solving the one-dimensional Schrödinger equation for the nucleus, we have obtained spectroscopic constants for both the ground state and 11 low-lying excited states.

Dissociation cross sections and rates in O + N collisions: molecular dynamics simulations combined with machine learning.

The collision-induced dissociation reaction of O (, ) + N, a fundamental process in nonequilibrium air flows around reentry vehicles, has been studied systematically by applying molecular dynamics simulations on the ', ' and ' potential energy surfaces of NO in a wide temperature range. In particular, we have directly investigated the role of the ' surface in this process and discussed the applicability of the simplified approximate rate models proposed by Esposito and Andrienko based on the lowest two surfaces. The present work indicates that the state-selected dissociation of O + N is dominated by the ' surface for all except for the low-lying O states.

Light-responsive organic polaritons from first principles.

Controlling the optical properties of light-responsive organic molecules is essential for their application in photonics. We demonstrate how light-responsive organic polaritons formed inside an optical cavity can be used to modify these properties based on first principles. Specifically, we study the excited state properties of the -azobenzene molecule and the free base tetraphenyl porphyrin (HTPP) molecule under weak to strong light-matter coupling.

Exhaustive state-specific dissociation study of the N2(Σg+1)+N(S4) system using QCT combined with a neural network method.

This work studies the exhaustive rovibrational state-specific collision-induced dissociation properties of the N2+N system by QCT (quasi-classical trajectory) combined with a neural network method based on the ab initio PES recently published by Varga et al. [Phys. Chem.

Real-time dynamic simulation of laser-induced N dissociation on two-dimensional graphene sheets.

Due to its relatively high inertness, nitrogen dissociation at ambient temperature and pressure has always been a challenging task. Plasmon driven photocatalysis has proved to be an effective method. Owing to their unique physical, chemical, and electronic properties, two-dimensional planar materials have become the most promising candidates to replace noble metal catalytic nitrogen reduction.

The role of the sextet potential energy surface in O + N inelastic collision processes.

We have performed molecular dynamics simulations of inelastic collisions between molecular oxygen and atomic nitrogen, employing the quasi-classical trajectory method on the new doublet, quartet, and sextet analytical potential energy surfaces of NO. A complete database of vibrationally detailed rate coefficients is constructed in a wide temperature range for high vibrational states up to = 25. In particular, the present work shows that the sextet potential energy surface plays a crucial role in the rovibrational relaxation process of O + N collisions.

Elastic and inelastic low-energy electron scattering from pyridine.

A comprehensive investigation of elastic and inelastic electron scattering from molecular pyridine is reported using the ab initio R-matrix method with the static exchange plus polarization and close-coupling approximations for incident energies up to 10 eV. The two well-known low-lying 1 B and 1 A shape resonances as well as a 2 B mixed-character resonance compare well with the theoretical and experimental results. We also detect five core-excited resonances (1 A, 1 B, 3 B, 2 A, and 4 B), which lie above the first electronic excitation threshold.

Modeling of laser-pulse induced small water cluster-(HO) ( = 1-10) decomposition on suitable metal cluster catalysts.

Understanding the microscopic mechanisms of electronic excitation in water clusters is a very important and challenging problem in a series of solar energy applications, such as solar water evaporation, photolysis, Here we employ real time-time-dependent density functional theory (RT-TDDFT) and Ehrenfest dynamics to investigate the photodissociation dynamic process of (HO) clusters and photoinduced charge transfer in them. The research presented here confirms that the plane tetramer, (HO), is the most difficult one to be dissociated under laser irradiation in the ten clusters for its high () symmetry; the overall order of the ease of decomposition is as follows: (HO) > (HO) > (HO) > (HO) > (HO) > (HO) > (HO) > (HO) > (HO) > (HO) > (HO). Plasmon catalyst-induced water splitting is a promising and feasible way to efficiently convert solar to chemical energy reducing the laser amplitude threshold significantly; and among the Ag, Au, Cu, Al chains and several Cu clusters with symmetry, the Cu chain seems to be the most cost-effective one.

Out-of-plane dipole-modulated photogenerated carrier separation and recombination at Janus-MoSSe/MoS van der Waals heterostructure interfaces: an time-domain study.

Out-of-plane mirror symmetry-breaking provides a powerful tool for engineering the electronic properties and the exciton behavior of two-dimensional materials. Here, by combining time-domain density functional theory with nonadiabatic dynamics, we investigate the underlying mechanism of how the vertical dipole moment modulates the photoexcited carrier transport and the electron-hole recombination dynamics in polar Janus MoSSe/MoS stacked heterostructures. It is shown that the stronger nonadiabatic coupling, interlayer-state delocalization and the built-in electric field caused by charge redistribution facilitate a more rapid photocarrier separation across the interface in the S/S stacked bilayer compared with the S/Se bilayer, explaining the experimentally observed stronger photoluminescence quenching effect in the S/S heterostructure.

-Matrix Calculation of Electron Collisions with Molecular Oxygen in Its Electronically Excited States.

Low-energy electron collisions with the XΣ- ground state and aΔ and bΣ+, the Herzberg states (cΣ, A'Δ, and AΣ+), and BΣ excited states of the O molecules are studied using the fixed-nucleus -matrix method. Integral elastic scattering and electronic excitation cross sections from the XΣ ground state overall agree well with the available experimental and theoretical results. The electronic (de-)excitation cross sections for the electron impact with the Herzberg states and the BΣ state are reported.

State-to-State Transition Study of the Exchange Reaction for N(S) and O(XΣ) Collision by Quasi-Classical Trajectory.

Based on the new A' and A' potential energy surfaces of NO fitted by Varga et al., we conducted a quasi-classical trajectory study on the N(S) +O(XΣ ) → NO(Π) + O(P) reaction, focusing on the high vibrational state up to ν = 25. For different rovibrational states of O, within the relative translational energy () range of 0.

Ab initio dynamics simulation of laser-induced photodissociation of phenol.

We theoretically investigated the photodissociation dynamics of phenol molecules steered by a sequence of temporally shaped femtosecond laser pulses with high intensity and ultrashort duration, via the real-time Time-Dependent Density Functional Theory (rt-TDDFT) combined with a Molecular Dynamics (MD) simulation. The principal findings of this research are that the phenol photodissociation can take place in 50 fs; the bonds broke sequentially; the degree of phenol molecular dissociation has a strong linear correlation with the intensity. For an incident laser being 800 nm-40 fs (wavelength-pulse duration), the threshold intensity is 7 × 10 W cm and the products are hydrogen from OH1 (phenolic hydroxyl group) and CHO-fragments.

Separation of C/C binary organic gas mixtures via flexible nanoporous carbon molecular sieves: DFT calculations and MD simulations.

The C/C hydrocarbon gas separation characteristics of nanoporous carbon molecular sieves (CMS) are studied using DFT calculations and MD simulations. To efficiently separate the equimolar CH/CH and CH/CH gas mixtures, CNT gas transport channels are embed between the polyphenylene membranes which created structural deformation for both CNT and membrane. The adsorption and permeation of gas molecules via CMS and the effect of nanochannel density and electric field on gas selectivity are analyzed.

Collision-Induced Rotational Excitation of CO by N(S) Atoms: A New Ab Initio Potential Energy Surface and Scattering Calculations.

Collisional excitations of CO molecules are significant to fully understand the physical and chemical processes of astrophysical and atmospheric environments. Rotational excitations of CO molecules induced by N(S) atoms have been studied for the first time. First, we have computed a new highly accurate ab initio potential energy surface (PES) of a CO-N(S) van der Waals complex.

New theoretical insights into the photoinduced carrier transfer dynamics in WS/WSe van der Waals heterostructures.

Shedding light on the dynamics of charge transfer is fundamental and important to understand the light-photocurrent power conversion in transition-metal dichalcogenide (TMD) heterostructures. Herein, based on time-dependent ab initio nonadiabatic molecular dynamics simulation, we studied the photoinduced carrier transfer dynamics in the WS2/WSe2 heterostructure and further analyzed the effects of stacking configuration and temperature. Our calculations show that the time scales of ultrafast hole transfer in the C7 and T stacking configurations are 35 fs and 30 fs, respectively, which are mainly caused by the adiabatic charge transfer mechanism.

Study on the Ti K, L, and M Edges of SrTiO and PbTiO.

The multiplet theory of free ions combined with crystal field theory is used to study core electron excitation of perovskites. This combined method is helpful to further identify transition peaks and comprehend the transition mechanism. In this paper, the core electron excitation of Ti K edge, L edges, and M edge in SrTiO and PbTiO is studied, and the identification of peak and the analysis of spectral shape are emphasized.

Effect of electric field on polarization and decomposition of RDX molecular crystals: a ReaxFF molecular dynamics study.

The polarization and decomposition of RDX crystal in external electric fields are simulated using molecular dynamics with ReaxFF force field. The results show that the molecular conformation of RDX is transformed from AAE to AAI in the electric field of 0.45 V/Å due to the polarization.

Kohn anomaly and van Hove singularity in IV and V group transition metals nitrides and carbides.

The superconducting behavior in IVB-VB group transition metal nitrides and carbides has generally been associated with the phonon anomaly and Fermi surface nesting. However, the origin of phonon anomaly has remained ambiguous (i.e.

MD simulation of methane adsorption properties on pillared graphene bubble models.

Pillared graphene bubble framework is selected as the methane storage vessel in this article. All investigations of methane adsorption are executed by using the MD simulations. The average adsorption energy of methane on different bubble models is between - 4.