Atoms

14 pages, 6427 KB

Open AccessArticle

Electron Scattering from Superheavy Elements: Copernicium and Oganesson

by Shruti Sarswat, Saumyashree Baral and Jobin Jose

Atoms 2025, 13(11), 94; https://doi.org/10.3390/atoms13110094 - 20 Nov 2025

Viewed by 1194

Superheavy elements are an ideal testbed for studying relativistic, exchange, and correlation effects in scattering phenomena. In this work, we investigate electron scattering from copernicium

(Z = 112)

and oganesson

(Z = 118)

atoms. Both the relativistic Dirac and [...] Read more.

Superheavy elements are an ideal testbed for studying relativistic, exchange, and correlation effects in scattering phenomena. In this work, we investigate electron scattering from copernicium

(Z = 112)

and oganesson

(Z = 118)

atoms. Both the relativistic Dirac and non-relativistic partial wave methods are employed to analyze the scattering dynamics, with the interaction between the projectile and target atom modeled within the framework of the optical potential approach. Our results demonstrate that relativistic, exchange, and correlation effects play a significant role in modifying the scattering cross-sections and scattering length, highlighting the influence of these interactions on the scattering processes from superheavy atomic systems. The work also attempts to identify common features of the scattering cross-section by comparing those of lighter elements in the same group. Full article

(This article belongs to the Section Atomic, Molecular and Nuclear Spectroscopy and Collisions)

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13 pages, 914 KB

Open AccessArticle

Antiprotonic Atoms as Gateways to HCI

by Lidia Lappo, Jakub Zieliński, Fredrik P. Gustafsson, Malgorzata Grosbart, Georgy Kornakov and Michael Doser

Atoms 2025, 13(11), 93; https://doi.org/10.3390/atoms13110093 - 19 Nov 2025

Viewed by 794

Abstract

The present study investigates the production of highly charged ions (HCIs) through the novel application of antiprotonic atoms and explores their potential for studying atomic and nuclear structures. Utilizing the Geant4 simulation toolkit, comprehensive simulations were conducted for all known isotopes with atomic [...] Read more.

The present study investigates the production of highly charged ions (HCIs) through the novel application of antiprotonic atoms and explores their potential for studying atomic and nuclear structures. Utilizing the Geant4 simulation toolkit, comprehensive simulations were conducted for all known isotopes with atomic numbers below 100. These simulations recorded key parameters of the resulting nuclear fragments, including mass, momentum, charge, and yield. The results obtained from this study offer valuable insights into the mechanisms of HCI production and provide a foundation for planning and analyzing future experimental investigations. This work demonstrates the feasibility of using antiprotonic atoms to advance nuclear and atomic physics research. Full article

(This article belongs to the Special Issue 21st International Conference on the Physics of Highly Charged Ions)

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18 pages, 1413 KB

Open AccessEditor’s ChoiceArticle

Hybrid Basis and Multi-Center Grid Method for Strong-Field Processes

by Kyle A. Hamer, Heman Gharibnejad, Luca Argenti and Nicolas Douguet

Atoms 2025, 13(11), 92; https://doi.org/10.3390/atoms13110092 - 17 Nov 2025

Viewed by 938

Abstract

We present a time-dependent framework that combines a hybrid basis, consisting of Gaussian-type orbitals (GTOs) and finite-element discrete-variable representation (FEDVR) functions, with a multicenter grid to simulate strong-field and attosecond dynamics in atoms and molecules. The method incorporates the construction of the orthonormal [...] Read more.

We present a time-dependent framework that combines a hybrid basis, consisting of Gaussian-type orbitals (GTOs) and finite-element discrete-variable representation (FEDVR) functions, with a multicenter grid to simulate strong-field and attosecond dynamics in atoms and molecules. The method incorporates the construction of the orthonormal hybrid basis, the evaluation of electronic integrals, a unitary time-propagation scheme, and the extraction of optical and photoelectron observables. Its accuracy and robustness are benchmarked on one-electron systems such as atomic hydrogen and the dihydrogen cation (

H_{2}^{+}

) through comparisons with essentially-exact reference results for bound-state energies, high-harmonic generation spectra, photoionization cross sections, and photoelectron momentum distributions. This work establishes the groundwork for its integration with quantum-chemistry methods, which is already operational but will be detailed in future work, thereby enabling ab initio simulations of correlated polyatomic systems in intense ultrafast laser fields. Full article

(This article belongs to the Special Issue Ab Initio Calculations in Atomic, Molecular, and Optical Physics: A Tribute to Barry Irwin Schneider)

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20 pages, 2241 KB

Open AccessArticle

Computational and Spectroscopic Investigation of Diaminomethane Formation: The Simplest Geminal Diamine of Astrochemical Interest

by Pravi Mishra, Parmanand Pandey, Rachana Singh, Manisha Yadav, Shivani, Aftab Ahamad, Alka Misra, Amritanshu Shukla and Poonam Tandon

Atoms 2025, 13(11), 91; https://doi.org/10.3390/atoms13110091 - 12 Nov 2025

Viewed by 1423

Abstract

A high-level ab initio characterization and formation of diaminomethane (DAM), the simplest geminal diamine, is presented to support its spectroscopic detection and astrochemical relevance in the interstellar medium. The C_2v DAM conformer is identified as the global minimum, while C₁ [...] Read more.

A high-level ab initio characterization and formation of diaminomethane (DAM), the simplest geminal diamine, is presented to support its spectroscopic detection and astrochemical relevance in the interstellar medium. The C_2v DAM conformer is identified as the global minimum, while C₁ DAM and C₂ DAM represent higher-energy local minima. The proposed reaction pathways are exothermic and proceed without activation barriers. Simulated infrared spectrum reproduces accurate key spectral signatures with several vibrational modes exhibiting strong IR intensities (>80 km mol⁻¹), particularly in the 800–3000 cm⁻¹ range and band shapes. Dipole moments and accurate rovibrational spectroscopic parameters, including rotational constants, anharmonic vibrational frequencies, quartic and sextic distortion constants, and nuclear quadrupole coupling constants are reported to assist with high-resolution spectroscopic identification. This study provides significant theoretical benchmarks for its formation and offers guidance for future laboratory spectroscopy and molecular searches in interstellar environments. Full article

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14 pages, 6876 KB

Open AccessArticle

Improving Quantitative Analysis of Lithium in Brines Using Laser-Induced Breakdown Spectroscopy with τ–Algorithm (τLIBS)

by Juan Molina M., Carlos Aragón, José A. Aguilera, César Costa-Vera and Diego M. Díaz Pace

Atoms 2025, 13(11), 90; https://doi.org/10.3390/atoms13110090 - 12 Nov 2025

Cited by 2 | Viewed by 1006

Abstract

In this work, a quantitative analysis of Li in natural brines was carried out by laser-induced breakdown spectroscopy (LIBS) assisted by the τ–algorithm for detailed analysis of the experimental line shapes (τLIBS). Brine samples were collected from different salars located in the Puna [...] Read more.

In this work, a quantitative analysis of Li in natural brines was carried out by laser-induced breakdown spectroscopy (LIBS) assisted by the τ–algorithm for detailed analysis of the experimental line shapes (τLIBS). Brine samples were collected from different salars located in the Puna plateau (Northwest Argentina) and analyzed by LIBS in the form of solid pressed pellets. The emission intensities of Li I, H_α, and Mg I–II lines were measured and spatially integrated along the line of sight with temporal resolution by using a high-spectral-resolution spectrometer equipped with an intensified charge-coupled device (iCCD) detector. The plasma was characterized through the determination of the electron density and the temperature. The τ–algorithm calculated the optical thicknesses of the Li I lines to generate synthetic intensity profiles that were subsequently fitted to the experimental spectra. By applying the developed τLIBS approach, valuable spectroscopic insight was recovered about the physical processes occurring in the plasma, such as self-absorption. The analytical process involved an univariate external calibration process using the resonant Li I line at 6707.7 Å measured from a series of Li standard samples. Self-absorption effects were evaluated and subsequently compensated. The final LIBS results, with an enhanced accuracy of 15%, were validated by crosschecking them against those obtained with the standard AAS method. Full article

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16 pages, 1425 KB

Open AccessEditor’s ChoiceArticle

Combining Physics and Machine Learning: Hybrid Models for Predicting Interatomic Potentials

by Kaoutar El Haloui, Nicolas Thome and Nicolas Sisourat

Atoms 2025, 13(11), 89; https://doi.org/10.3390/atoms13110089 - 10 Nov 2025

Cited by 2 | Viewed by 2056

Abstract

Constructing accurate Potential Energy Surfaces (PES) is a central task in molecular modeling, as it determines the forces governing nuclear motion and enables reliable quantum dynamics simulations. While ab initio methods can provide accurate PES, they are computationally prohibitive for extensive applications. Alternatively, [...] Read more.

Constructing accurate Potential Energy Surfaces (PES) is a central task in molecular modeling, as it determines the forces governing nuclear motion and enables reliable quantum dynamics simulations. While ab initio methods can provide accurate PES, they are computationally prohibitive for extensive applications. Alternatively, analytical physics-based models such as the Morse potential offer efficient solutions but are limited by their rigidity and poor generalization to excited states. In recent years, neural networks have emerged as powerful tools for determining PES, due to their universal function approximation capabilities, but they require large training datasets. In this work, we investigate hybrid-residual modeling approaches that combine physics-based potentials with neural network corrections, aiming to leverage both physical priors and data adaptability. Specifically, we compare three hybrid models—APHYNITY, Sequential Phy-ML, and PhysiNet—in their ability to reconstruct the potential energy curve of the ground and first excited states of the hydrogen molecule. Each model integrates a simplified physical representation with a neural component that learns the discrepancies from accurate reference data. Our findings reveal that hybrid models significantly outperform both standalone neural networks and pure physics-based models, especially in low-data regimes. Notably, APHYNITY and Sequential Phy-ML exhibit better generalization and maintain accurate estimation of physical parameters, underscoring the benefits of explicit physics incorporation. Full article

(This article belongs to the Special Issue Artificial Intelligence for Quantum Sciences)

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15 pages, 1029 KB

Open AccessEditor’s ChoiceArticle

Single Ionization with Dressed Projectiles: An Improved Theory for Both Long- and Short-Range Interactions

by Nicolás J. Esponda, Michele A. Quinto, Roberto D. Rivarola and Juan M. Monti

Atoms 2025, 13(11), 88; https://doi.org/10.3390/atoms13110088 - 9 Nov 2025

Viewed by 655

Abstract

In this work, we present a theoretical model to investigate electron emission in collisions between dressed ions with He atoms and H₂ molecules. The projectile potential is described as the sum of a long- and short-range terms. The last term includes a [...] Read more.

In this work, we present a theoretical model to investigate electron emission in collisions between dressed ions with He atoms and H₂ molecules. The projectile potential is described as the sum of a long- and short-range terms. The last term includes a screening function that has its maximum at short distances. The present model is based on the Continuum Distorted Wave Eikonal Initial State (CDW-EIS) theory, but the Eikonal approximation is only made within the long-range transition amplitude. This now leads to physically correct predictions, whenever dressed projectiles are involved, in the binary-encounter peak. Indeed, double-differential cross-sections spectra is calculated and compared with existing experimental data, finding that this model is capable of reproducing some well-known phenomena depending on the projectile charge state. Namely, the dependence of the binary-encounter peak magnitude with the projectile charge state. Full article

(This article belongs to the Section Atomic, Molecular and Nuclear Spectroscopy and Collisions)

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38 pages, 792 KB

Open AccessArticle

First and Second Law of Thermodynamics Constraints in the Lifshitz Theory of Dispersion Forces

by Fabrizio Pinto

Atoms 2025, 13(11), 87; https://doi.org/10.3390/atoms13110087 - 5 Nov 2025

Viewed by 2202

Abstract

The presence of dominant interatomic dispersion forces on the nanoscale holds the promise for breakthrough applications in key areas of quantum sensing, such as accelerometry, as well as nano-manipulation and energy storage. In order to do work, nano-machines enabled by dispersion forces must [...] Read more.

The presence of dominant interatomic dispersion forces on the nanoscale holds the promise for breakthrough applications in key areas of quantum sensing, such as accelerometry, as well as nano-manipulation and energy storage. In order to do work, nano-machines enabled by dispersion forces must exchange energy with the surrounding environment. Such processes can be described in terms of thermodynamical engine cycles involving individual atoms or material boundaries, separated by possibly empty gaps and interacting via time-dependent dispersion forces. The fundamental strategy indispensable to achieve dispersion force time-modulation, demonstrated experimentally by independent groups on different scales, is based on the illumination of interacting, semiconducting elements by appropriate radiation beams. Here we analyze the operation of ideal nano-engines in the quasi-static regime by means of the Lifshitz theory of dispersion forces involving semiconducting boundary or atom irradiation. Firstly, we verify that the First Law of Thermodynamics is satisfied so that the total energy of the system is rigorously conserved. Secondly, we show that, within this first approximate treatment, the Second Law of Thermodynamics may be violated for extremely small interboundary gap widths. We identify important limitations to be addressed to determine whether this is a reliable conclusion. The technological and historic backdrops are presented, and important topics for future research are identified. Full article

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8 pages, 467 KB

Open AccessArticle

The Arrow of Time in Quantum Theory

by Jean-Patrick Connerade

Atoms 2025, 13(11), 86; https://doi.org/10.3390/atoms13110086 - 26 Oct 2025

Viewed by 2355

Abstract

In Classical Mechanics, time is reversible, i.e., it implies no particular choice: only the observer knows in which direction it flows. The present article re-examines whether this remains true in Quantum Mechanics. In the context of Atomic Physics, it is concluded that the [...] Read more.

In Classical Mechanics, time is reversible, i.e., it implies no particular choice: only the observer knows in which direction it flows. The present article re-examines whether this remains true in Quantum Mechanics. In the context of Atomic Physics, it is concluded that the existence of an arrow of time depends on the manner in which the radiation field is introduced, which must be non-perturbative. Full article

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Atoms, Volume 13, Issue 11 (November 2025) – 9 articles

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