Collision Energy Research Articles

Construction of diabatic potential energy surfaces for the SiH2+ system and dynamics studies of the Si+(2P1/2, 3/2) + H2 reaction.

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 abinitio 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.

Probing Inert Triplet Model at a multi-TeV muon collider via vector boson fusion with forward muon tagging

This study investigates the potential of a multi-TeV Muon Collider (MuC) for probing the Inert Triplet Model (ITM), which introduces a triplet scalar field with hypercharge Y = 0 to the Standard Model. The ITM stands out as a compelling Beyond the Standard Model scenario, featuring a neutral triplet T0 and charged triplets T±. Notably, T0 is posited as a dark matter (DM) candidate, being odd under a Z2 symmetry. Rigorous evaluations against theoretical, collider, and DM experimental constraints corner the triplet scalar mass to a narrow TeV-scale region, within which three benchmark points are identified, with T± masses of 1.21 TeV, 1.68 TeV, and 3.86 TeV, for the collider study. The ITM’s unique TTVV four-point vertex, differing from fermionic DM models, facilitates efficient pair production through Vector Boson Fusion (VBF). This characteristic positions the MuC as an ideal platform for exploring the ITM, particularly due to the enhanced VBF cross-sections at high collision energies. To address the challenge of the soft decay products of T± resulting from the narrow mass gap between T± and T0, we propose using Disappearing Charged Tracks (DCTs) from T± and Forward muons as key signatures. We provide event counts for these signatures at MuC energies of 6 TeV and 10 TeV, with respective luminosities of 4 ab−1 and 10 ab−1. Despite the challenge of beam-induced backgrounds contaminating the signal, we demonstrate that our proposed final states enable the MuC to achieve a 5σ discovery for the identified benchmark points, particularly highlighting the effectiveness of the final state with one DCT and one Forward muon.

Jet angularities in dijet production in proton-proton and heavy-ion collisions at RHIC

We study jet angularities for dijet production at the Relativistic Heavy Ion Collider (RHIC) in proton-proton (pp) and nucleus-nucleus (AA) collisions at 200 GeV nucleon-nucleon center-of-mass collision energy. In particular, we provide NLL resummed predictions for angularity observables of groomed and ungroomed jets produced in pp collisions matched to next-to-leading order QCD calculations resulting in NLO + NLL′ accuracy. Our parton-level predictions are corrected for non-perturbative effects, such as hadronization and underlying event, using parton-to-hadron level transfer matrices obtained with the Sherpa event generator. Furthermore, we use the Q-Pythia and Jewel generators to estimate the impact of the interaction between quarks and gluons produced by the parton shower with the dense medium formed in heavy-ion collisions on the considered jet angularities.

Novel Multi‐configuration Elastic Actuator with Controllable Energy Flow and Power Modulation for Dynamic Energy Robot Systems

Designing actuators that can modulate power, achieve high energy efficiency, and ensure safe collision remains a challenge, especially for dynamic energy robot systems (DERS) with high‐performance requirements. Herein, a novel multi‐configuration elastic actuator (MCEA) is proposed based on a controllable planetary differential mechanism (PDM) with one power port from three springs. These springs, positioned between the inner gear ring and the fixed housing shell, are regulated by a single servo motor through a ratchet–pawl mechanism. This setup enables the springs to absorb energy during collisions, reducing impact and subsequently releasing this energy to boost power output. The inner gear ring functions as a controllable one‐way rotating element, acting either as an input or output for power. The MCEA's ability to manage power modulation and energy flow is demonstrated through experiments that highlight its potential for safe collision management, energy recycling, and power modulation. Experiment results indicate that the maximum output power of the MCEA in the proposed hybrid elastic actuation (HEA) mode is 8.05 times higher than that in the traditional actuation (TA) mode. A single‐legged robot with a four‐link mechanism is also built to validate the considerable performance in the application of legged robots, showing considerable adaptability and prospects for DERS.

A Reverse Thinking Based on Partially Methylated Aldononitrile Acetates to Analyze Glycoside Linkages of Polysaccharides Using Liquid Chromatography-Multiple Reaction Monitoring Mass Spectrometry.

Glycoside linkage analyses of medicine and food homologous plant polysaccharides have always been a key point and a difficulty of structural characterization. The gas chromatography-mass spectrometry (GC-MS) method is one of the commonly used traditional techniques to determine glycoside linkages via partially methylated alditol acetates and aldononitrile acetates (PMAAs and PMANs). Due to the simplicity of derivatization and the highly structural asymmetry of PMANs, reverse thinking is proposed using liquid chromatography-electrospray ionization-multiple reaction monitoring mass spectrometry (LC-ESI-MRM-MS) for the first time to directly determine the neutral and acidic glycosyl linkages of polysaccharides. The complete characterization of glycoside linkages deduced from PMANs was achieved using a combination of tR values, characteristic MRM ion pairs, diagnostic ESI+-MS/MS fragmentation ions (DFIs), and optimal collision energy (OCE). The DFI and OCE parameters were confirmed to be effective for the auxiliary discrimination of some isomers of the PMANs. The practicality of LC-ESI+-MRM-MS was further verified by analyzing the glycoside linkages of polysaccharides in five medicine and food homologous plants. This method can serve as an alternative to GC-MS for the simultaneous determination of neutral and acidic glycosyl linkages in polysaccharides.

A Globally Accurate Neural Network Potential Energy Surface and Quantum Dynamics Studies on Be+(2S) + H2/D2 → BeH+/BeD+ + H/D Reactions.

Chemical reactions between Be+ ions and H2 molecules have significance in the fields of ultracold chemistry and astrophysics, but the corresponding dynamics studies on the ground-state reaction have not been reported because of the lack of a global potential energy surface (PES). Herein, a globally accurate ground-state BeH2+ PES is constructed using the neural network model based on 18,657 ab initio points calculated by the multi-reference configuration interaction method with the aug-cc-PVQZ basis set. On the newly constructed PES, the state-to-state quantum dynamics calculations of the Be+(2S) + H2(v0 = 0; j0 = 0) and Be+(2S) + D2(v0 = 0; j0 = 0) reactions are performed using the time-dependent wave packet method. The calculated results suggest that the two reactions are dominated by the complex-forming mechanism and the direct abstraction process at relatively low and high collision energies, respectively, and the isotope substitution has little effect on the reaction dynamics characteristics. The new PES can be used to further study the reaction dynamics of the BeH2+ system, such as the effects of rovibrational excitations and alignment of reactant molecules, and the present dynamics data could provide an important reference for further experimental studies at a finer level.

Full quantum calculations of the line shape for H2O perturbed by Ar at temperatures from 20 to 300 K.

This work theoretically studied the spectral line shape of H2O perturbed by Ar in the temperature range of 20-300K for the pure rotational lines below 360cm-1, as well as three lines (31, 2 ← 44, 1, 54, 2 ← 41, 3, and 73, 5 ← 60, 6) in the v2 band. In order to perform precise dynamical calculations at low collision energies, a full-dimensional long-range potential energy surface was constructed for the H2O-Ar system for the first time to correct the long range of our newly developed intermolecular potential energy surface. Subsequently, the six line-shape parameters (pressure-broadening and -shifting parameters, their speed dependencies, and the complex Dicke parameters) were determined from the generalized spectroscopic cross section by the full quantum time-independent close-coupling approach on this new potential energy surface. Our theoretical results are in good agreement with the available experimental observations. Furthermore, the influence of the speed-dependence and Dicke narrowing effects on the line contour was revealed by comparing the differences among the Hartmann-Tran, quadratic-speed-dependent Voigt, and Voigt profiles. The temperature dependence of each line-shape parameter was further parameterized using the triplet-power-law for three pure rotational 61, 6 ← 52, 3, 41, 4 ← 32, 1, and 31, 3 ← 22, 0 lines. These line-shape parameters will provide a comprehensive set of theoretical references for subsequent experimental measurements.

Production of hidden-heavy and double-heavy hadronic molecules at the Z factory of CEPC

With a clean environment and high collision energy, the Circular Electron Positron Collider (CEPC) would be an excellent facility for heavy flavor physics. Using the Monte Carlo event generator ythia, we simulate the production of the charmed (bottom) hadron pairs in the electron-positron collisions at the Z factory of CEPC, and the inclusive production rates for typical candidates of the hidden/double-charm and hidden/double-bottom S-wave hadronic molecules are estimated at an order-of-magnitude level with the final state interactions after the hadron pair production. The predicted cross sections for the hidden-charm meson-meson molecules X(3872) and Zc(3900) are at pb level, which are about two to three orders of magnitude larger than the production cross sections for the double-charm meson-meson molecules Tcc and Tcc*, as the double-charmed ones require the production of two pairs of cc¯ from the Z boson decay. The production cross sections for the hidden-charm pentaquark states Pc and Pcs as meson-baryon molecules are a few to tens of fb, which are about one magnitude larger than those of the possible hidden-charm baryon-antibaryon and double-charm meson-baryon molecules. In the bottom sector, the production cross sections for the Zb states as B(*)B¯* molecules are about tens to hundreds of fb, indicating 106–107 events from a two-year operation of CEPC, and the expected events from the double-bottom molecules are about 2–5 orders of magnitude smaller than the Zb states. Our results shows great prospects of probing heavy exotic hadrons at CEPC. Published by the American Physical Society 2024

A hydrolyzed N-propionylthiosuccinimide linker is cleaved by metastable fragmentation, increasing reliability of conjugation site identification in conjugate vaccines.

Conjugation sites are a quality attribute of conjugate vaccines. Proteolysis of bioconjugates synthesized by maleimide-thiol chemistry generates type 2 peptides with a hydrolyzed thiosuccinimide linker containing information on the conjugation sites. A mass spectrometry (MS)-cleavable linker could make the identification of conjugation sites by MS more reliable. Four synthetic type 2 peptides with a hydrolyzed thiosuccinimide linker were analyzed by matrix-assisted laser desorption ionization (MALDI) MS/MS with and without collision gas. These peptides were also partially labeled with 18O in the linker to confirm the proposed fragmentation mechanism. A conjugate vaccine with the hydrolyzed thiosuccinimide linker was reduced and S-alkylated, digested with trypsin and analyzed by liquid chromatography-MS/MS using collision-induced dissociation (CID) and higher-energy collisional dissociation (HCD) fragmentation methods at a normalized collision energy of 30. A metastable fragmentation preferentially cleaves the newly formed pseudopeptide bond within the hydrolyzed thiosuccinimide linker of type 2 peptides to yield P + 71 and C + 98 ions. These ions make the assignment of conjugation sites more reliable. Partial 18O-labeling and MS/MS analysis confirmed the proposed structures. CID produces these ions as the two most intense signals more favorably than HCD. The latter also yields these ions, guarantees better sequence coverage and promotes other fragmentations in the linker. Hydrolyzed thiosuccinimide linker is cleavable in MALDI and electrospray ionization MS/MS analysis by a gas-phase metastable fragmentation. The resulting fragment ions (P + 71 and C + 98) make the identification of conjugation sites more reliable. These results could be extended to self-hydrolyzing maleimides, which efficiently stabilize the thiosuccinimide linker upon hydrolysis, in antibody-drug conjugates.

Exploring the collision, acoustic and thermal energy dissipation distribution of discrete mass

This research delves into the transfer and loss of energy in a discrete mass when subjected to forced vibration. Using discrete element method (DEM), we analyzed the dynamic behavior of regular spherical granular assemblies and the energy distribution characteristics under different excitation frequencies and reduced accelerations. Moreover, the energy transfer and dissipation process of granular assemblies under different vibration states are studied using an experimental method. The results show that the granular assemblies will produce collision energy dissipation, thermal energy dissipation, acoustic energy dissipation and other forms of energy dissipation in the forced vibration state and the proportion of different energy dissipation under different excitation is given. The collision and friction of granular assemblies are the key to affecting other forms of energy dissipation. When the excitation increases, the energy dissipation forms are generated inside the granular assemblies, and the proportion of collision energy dissipation of the granular assemblies increases. The acoustic energy above 20 kHz occupies the main part of the acoustic energy dissipation. Thermal energy consumption always exists, which takes a long time to play a role. The granular also have other forms of energy loss, which is hard to be measured, including Rayleigh waves generated by granular collision. In this study, the relationship between the forced vibration state of the granular assemblies and the energy loss distribution is established. Various types of energy transfer and conversion distribution which further enriches the energy dissipation of discrete element calculation of the granular assemblies is discussed and provides a reference for the energy loss analysis of the granular assemblies.

Dynamic deformation behavior of Fe-0.22C-1.65Si-1.98Mn quenching and partitioning steel over a wide range of strain rates and constitutive model establishment

During traffic accidents, automobiles often experience rapid deformation at high strain rates spanning from 10² to 10³ s⁻¹. The dynamic deformation behavior and the constitutive model of the materials are crucial for precisely analyzing and simulating vehicle collisions and damage. This study focuses on a high-strength quenching-partitioning steel (Q&P steel) compositionally tailored for automotive applications, specifically Fe-0.22C-1.65Si-1.98Mn. Tensile tests were conducted under quasi-static (10⁻⁴–10⁻¹ s⁻¹) and dynamic (1–10³ s⁻¹) conditions to obtain stress-strain data, based on which the deformation behavior and instability mechanism of the Q&P steel were revealed. A Johnson-Cook (J-C) constitutive model was established to predict the stress-strain behavior. This model was further improved by incorporating the nonlinear influence of strain rate on stress, resulting in a significant reduction of prediction error by 60.9 % in the high strain rate range. Based on the modified J-C model, the finite element simulations of the high-speed collision for U-shaped and tubular components were conducted. The simulations exhibit excellent agreement with experimental results, thus confirming the accuracy of the model in predicting high-speed deformation behavior of the Q&P steel. This validation enables precise simulations of dynamic collision characteristics and energy absorption.

Identification of a Chimera Mass Spectrum of Isomeric Lipid A Species Using Negative Ion Tandem Mass Spectrometry.

The toxic nature of bacterial endotoxins is affected by the structural details of lipid A, including the variety and position of acyl chains and phosphate group(s) on its diglucosamine backbone. Negative-ion mode tandem mass spectrometry is a primary method for the structure elucidation of lipid A, used independently or in combination with separation techniques. However, it is challenging to accurately characterize constitutional isomers of lipid A extracts by direct mass spectrometry, as the elemental composition and molecular mass of these molecules are identical. Thus, their simultaneous fragmentation leads to a composite, so-called chimera mass spectrum. The present study focuses on the phosphopositional isomers of the classical monophosphorylated, hexaacylated Escherichia coli-type lipid A. Collision-induced dissociation (CID) was performed in an HPLC-ESI-QTOF system. Energy-resolved mass spectrometry (ERMS) was applied to uncover the distinct fragmentation profiles of the phosphorylation isomers. A fragmentation strategy applying multi-levels of collision energy has been proposed and applied to reveal sample complexity, whether it contains only a 4'-phosphorylated species or a mixture of 1- and 4'-phosphorylated variants. This comparative fragmentation study of isomeric lipid A species demonstrates the high potential of ERMS-derived information for the successful discrimination of co-ionized phosphorylation isomers of hexaacylated lipid A.

Dependence of thermodynamic quantities at freeze-out on pseudorapidity and collision energy in p-p collisions at LHC energies* *Supported by Princess Nourah bint Abdulrahman University Researchers Supporting Project number (PNURSP2024R106), Princess Nourah bint Abdulrahman University, Riyadh, Saudi Arabia. In addition, the authors extend their appreciation to the Deanship of Scientific Research at Northern Border University, Arar, KSA for funding this research

The transverse momentum distributions of charged hadrons produced in proton-proton collisions at center-of-mass energies ( ) of 0.9 TeV and 2.36 TeV, as measured by the CMS detector at the Large Hadron Collider (LHC), have been analyzed within various pseudorapidity classes utilizing the thermodynamically consistent Tsallis distribution. The fitting procedure resulted in the key parameters, namely, effective temperature (T), non-extensivity parameter (q), and kinetic freezeout volume (V). Additionally, the mean transverse momentum ( ) and initial temperature (Ti ) of the particle source are determined through the fit function and string percolation method, respectively. An alternative method is employed to calculate the kinetic freezeout temperature ( ) and transverse flow velocity ( ) from T. Furthermore, thermodynamic quantities at the freezeout, including energy density (ε), particle density (n), entropy density (s), pressure (P), and squared speed of sound ( ), are computed using the extracted T and q. It is also observed that, with a decrease in pseudorapidity, all thermodynamic quantities except V and q increase. This trend is attributed to greater energy transfer along the mid pseudorapidity. q increases towards higher values of pseudorapidity, indicating that particles close to the beam axis are far from equilibrium. Meanwhile, V remains nearly independent of pseudorapidity. The excitation function of these parameters (q) shows a direct (inverse) correlation with collision energy. The ε, n, s, and P show a strong dependence on collision energies at low pseudorapidities. Explicit verification of the thermodynamic inequality suggests the formation of a highly dense droplet-like Quark-Gluon Plasma (QGP). Additionally, the inequality is explicitly confirmed, aligning with the evolution of the produced fireball.

Quantitative comparison of bile acid glucuronides sub-metabolome between intrahepatic cholestasis and healthy pregnant women.

Because of the pathological indication and the physiological functions, bile acids (BAs) have occupied the research hotspot in recent decades. Although extensive efforts have been paid onto BAs sub-metabolome characterization, as the subfamily, BA glucuronides (gluA-BAs) profile is seldom concerned. Here, we made efforts to develop a LC-MS/MS program enabling quantitative gluA-BAs sub-metabolome characterization and to explore the differential species in serum between intrahepatic cholestasis of pregnancy (ICP) patients and healthy subjects. To gain as many authentic gluA-BAs as possible, liver microsomes from humans, rats, and mice were deployed to conjugate glucuronyl group to authentic BAs through in vitro incubation. Eighty gluA-BAs were captured and subsequently served as authentic compounds to correlate MS/MS spectral behaviors to structural features using squared energy-resolved MS program. Optimal collision energy (OCE) of [M-H]->[M-H-176.1]- was jointly administrated by [M-H]- mass and glucuronidation site, and identical exciting energies corresponding to 50% survival rate of 1st-generation fragment ion (EE50) were observed merely when the aglycone of a gluA-BA was consistent with the suspected structure. Through integrating high-resolution m/z, OCE, and EE50 information to identify gluA-BAs in a BAs pool, 97 ones were found and identified, and further, quantitative program was built for all annotated gluA-BAs by assigning OCEs to [M-H]->[M-H-176.1]- ion transitions. Quantitative gluA-BAs sub-metabolome of ICP was different from that of the healthy group. More GCDCA-3-G, GDCA-3-G, TCDCA-7-G, TDCA-3-G, and T-β-MCA-3-G were distributed in the ICP group. Above all, this study not only offered a promising analytical tool for in-depth gluA-BAs sub-metabolome characterization, but also clarified gluA-BAs allowing the differentiation of ICP and healthy subjects.

Softening of the hypertriton transverse momentum spectrum in heavy-ion collisions

Understanding the properties of hypernuclei helps to constrain the interaction between hyperon and nucleon, which is known to play an essential role in determining the properties of neutron stars. Experimental measurements have suggested that the hypertriton (HΛ3), the lightest hypernucleus, exhibits a halo structure with a deuteron core encircled by a Λ hyperon at a distance of about 10 fm. This large Λ−d distance in HΛ3 wave function is found to cause a suppressed HΛ3 yield and a softening of its transverse momentum (pT) spectrum in relativistic heavy-ion collisions. Within the coalescence model based on nucleons and Λ hyperons from a microscopic hybrid hydro model with a hadronic afterburner for nuclear cluster production in Pb-Pb collisions at sNN= 5.02 TeV, we show how this softening of the hypertriton pT spectrum appears and leads to a smaller mean pT for HΛ3 than for helium-3 (3He). The latter is opposite to the predictions from the blast-wave model which assumes that HΛ3 and 3He are thermally produced at the kinetic freeze-out of heavy-ion collisions. The discovered quantum mechanical softening of the (anti-)hypertriton spectrum can be experimentally tested in relativistic heavy-ion collisions at different collision energies and centralities and used to obtain valuable insights to the mechanisms for light (hyper-)nuclei production in these collisions.

Contribution of coherent electron production to measurements of heavy-flavor decayed electrons in heavy-ion collisions

Heavy quarks, produced at early stages of heavy-ion collisions, are an excellent probe of the Quark-Gluon Plasma (QGP) also created in these collisions. Electrons from open heavy-flavor hadron decays (HFE) are good proxies for heavy quarks, and have been measured extensively in the last two decades to study QGP properties. These measurements are traditionally carried out by subtracting all known background sources from the inclusive electron sample. More recently, a significant enhancement of e+e-\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$e^+e^-$$\\end{document} pair production at very low transverse momenta was observed in peripheral heavy-ion collisions. The production characteristics is consistent with coherent photon–photon interactions, which should also constitute a background source to the HFE measurements. In this article, we provide theoretical predictions for the contribution of coherent electron production to HFEs as a function of transverse momentum, centrality and collision energy in Au+Au and Pb+Pb collisions.

Streamlining the Analysis of Proteins from Snake Venom.

Investigating snake venom is necessary for developing new treatments for envenoming and harnessing the therapeutic potential that lies within venom toxins. Despite considerable efforts in previous research, several technical challenges remain for characterizing the individual components within such complex mixtures. Here, we present native and top-down mass spectrometry (MS) workflows that enable the analysis of individual venom proteins within complex mixtures and showcase the utility of these methodologies on King cobra (Ophiophagus hannah) venom. First, we coupled ion mobility spectrometry for separation and electron capture dissociation for charge reduction to resolve highly convoluted mass spectra containing multiple proteins with masses ranging from 55 to 127 kDa. Next, we performed a top-down glycomic analysis of a 25.5 kDa toxin, showing that this protein contains a fucosylated complex glycan. Finally, temperature-controlled nanoelectrospray mass spectrometry facilitated the top-down sequence analysis of a β-cardiotoxin, which cannot be fragmented by collisional energy due to its disulfide bond pattern. The work presented here demonstrates the applicability of new and promising MS methods for snake venom analysis.

Modeling collisional kinetic energy damping, heating, and cooling of ions in mass spectrometers: A tutorial perspective

Many powerful methods in mass spectrometry rely on activation of ions by high-energy collisions with gas particles. For example, multiple Collision Induced Dissociation (CID) has been used for many years to determine structural information for ions ranging from small organics to large, native-like protein complexes. More recently, Collision Induced Unfolding (CIU) has proved to be a very powerful method for understanding high-order protein structure and detecting differences between similar proteins. Quantifying the thermochemistry underlying dissociation/unfolding in these experiments can be quite challenging without reliable models of ion heating and cooling. Established physical models of CID are valuable in predicting ion heating but do not explicitly include mechanisms for cooling, which may play a large part in CID/CIU in modern instruments. Ab initio and Molecular Dynamics methods are extremely computationally expensive for modeling CID/CIU of large analytes such as biomolecular ions. In this tutorial perspective, limiting behaviors of ion kinetic energy damping, heating, and cooling set by “extreme” cases are explored, and an Improved Impulsive Collision Theory and associated software (“Ion Simulations of the Physics of Activation”, IonSPA) are introduced that can model all of these for partially inelastic collisions. Finally, examples of modeled collisional activation of native-like protein ions under realistic experimental conditions are discussed, with an outlook toward the use of IonSPA in accessing the thermochemical information hidden in CID breakdown curves and CIU fingerprints.

Odderon contribution in light of the LHC low- t data

We perform the analysis of elastic scattering pp and p¯p data at low momentum transfer |t|<0.1 GeV2 within large collider energy interval s=50 GeV–13 TeV in order to evaluate quantitatively the possible Odderon contribution. We use the two-channel eikonal model, which naturally accounts for the screening of the Odderon amplitude by C-even (Pomeron) exchanges. Published by the American Physical Society 2024

A Neural Network Potential Energy Surface and Quantum Dynamics Study of Ca(1S) + H2(v 0 = 0, j 0 = 0) → CaH + H Reaction.

The reactive collision between Ca and H2 molecules has attracted great interest experimentally due to the key role of the product CaH molecule in the field of astrophysics and cold molecules. However, quantum dynamics calculations for this system have not been reported due to the lack of a global potential energy surface (PES). Herein, a globally accurate PES of the ground-state CaH2 is developed by combining 11365 high-level ab initio points and permutation invariant polynomial neural network method. Based on the newly constructed PES, the state-to-state quantum dynamics calculations for the Ca(1S) + H2 (v 0 = 0, j 0 = 0) → CaH + H reaction are carried out using the time-dependent wave packet method. The dynamic results reveal that the reaction follows the complex-forming mechanism near the reactive threshold, whereas both the indirect insertion mechanism and direct abstraction mechanism have effects at higher collision energies. The newly constructed PES can be used to further study the influence of isotope substitution, rovibrational excitation, and spatial orientation of reactant molecules on reaction dynamics.