You seem to have javascript disabled. Please note that many of the page functionalities won't work as expected without javascript enabled.

Search for Articles:

Title / Keyword

Author / Affiliation / Email

Journal

Article Type

Advanced Search

Section

Special Issue

Volume

Issue

Number

Page

Logical OperatorOperator

Search Text

Search Type

Observing the Ionization of Metastable States of Sn¹⁴⁺ in an Electron Beam Ion Trap
Multi-Configuration Dirac–Hartree–Fock Calculations of Pr⁹⁺ and Nd¹⁰⁺: Configuration Resolution and Probing Fine-Structure Constant Variation
Energy Levels, Lifetimes, and Transition Properties for N iii – v
Polarization Reconstruction Based on Monte Carlo Simulations for a Compton Polarimeter

Journal Description

Atoms

Atoms is an international, peer-reviewed, open access journal on all aspects of the atom published monthly online by MDPI.

Open Access— free for readers, with article processing charges (APC) paid by authors or their institutions.
High Visibility: indexed within Scopus, ESCI (Web of Science), Astrophysics Data System, Inspec, CAPlus / SciFinder, INSPIRE, and other databases.
Journal Rank: CiteScore - Q2 (Nuclear and High Energy Physics)
Rapid Publication: manuscripts are peer-reviewed and a first decision is provided to authors approximately 20.3 days after submission; acceptance to publication is undertaken in 3.7 days (median values for papers published in this journal in the first half of 2025).
Recognition of Reviewers: reviewers who provide timely, thorough peer-review reports receive vouchers entitling them to a discount on the APC of their next publication in any MDPI journal, in appreciation of the work done.

Impact Factor: 1.5 (2024); 5-Year Impact Factor: 1.5 (2024)

Imprint Information Journal Flyer Open Access ISSN: 2218-2004

Latest Articles

15 pages, 591 KB

Open AccessArticle

Single Electron Capture by Dressed Projectiles Within the Distorted Wave Formalism

by Michele Arcangelo Quinto, Juan Manuel Monti and Roberto Daniel Rivarola

Atoms 2025, 13(10), 84; https://doi.org/10.3390/atoms13100084 - 3 Oct 2025

Single electron capture in collisions involving neutral hydrogen atoms impacted by highly charged dressed projectiles is theoretically investigated using the distorted wave formalism. A series of continuum distorted wave approximations is employed to investigate the electron capture from neutral hydrogen atom impact by [...] Read more.

Single electron capture in collisions involving neutral hydrogen atoms impacted by highly charged dressed projectiles is theoretically investigated using the distorted wave formalism. A series of continuum distorted wave approximations is employed to investigate the electron capture from neutral hydrogen atom impact by boron and carbon projectiles. The projectile potential is described using a two-parameter analytical Green–Sellin–Zachor (GSZ) model potential. The theoretical prediction of total cross sections are compared against other theories and experiments. We looked at a very broad range of collision energies, from 10 keV/u up to 10 MeV/u. In addition, the state-selective cross sections for boron ions are presented. Full article

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

28 pages, 3057 KB

Open AccessArticle

Proton Interactions with Biological Targets: Inelastic Cross Sections, Stopping Power, and Range Calculations

by Camila Strubbia Mangiarelli, Verónica B. Tessaro, Michaël Beuve and Mariel E. Galassi

Atoms 2025, 13(10), 83; https://doi.org/10.3390/atoms13100083 - 24 Sep 2025

Proton therapy enables precise dose delivery to tumors while sparing healthy tissues, offering significant advantages over conventional radiotherapy. Accurate prediction of biological doses requires detailed knowledge of radiation interactions with biological targets, especially DNA, a key site of radiation-induced damage. While most biophysical [...] Read more.

Proton therapy enables precise dose delivery to tumors while sparing healthy tissues, offering significant advantages over conventional radiotherapy. Accurate prediction of biological doses requires detailed knowledge of radiation interactions with biological targets, especially DNA, a key site of radiation-induced damage. While most biophysical models (LEM, mMKM, NanOx) rely on water as a surrogate, this simplification neglects the complexity of real biomolecules. In this work, we calculate the stopping power and range of protons in liquid water, dry DNA, and hydrated DNA using semi-empirical cross sections for ionization, electronic excitation, electron capture, and electron loss by protons and neutral hydrogen in the 10 keV–100 MeV energy range. Additionally, ionization cross sections for uracil are computed to explore potential differences between DNA and RNA damage. Our results show excellent agreement with experimental and ab initio data, highlighting significant deviations in stopping power and range between water and DNA. Notably, the stopping power of DNA exceeds that of water at most energies, reducing proton ranges in dry and hydrated DNA by up to 20% and 26%, respectively. These findings provide improved input for Monte Carlo simulations and biophysical models, enhancing RBE predictions and dose accuracy in hadrontherapy. Full article

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

► Show Figures

Figure 1

12 pages, 541 KB

Open AccessArticle

Integral Cross Sections and Transport Properties for Electron–Radon Scattering over a Wide Energy Range (0–1000 eV) and a Reduced Electric Field Range (0.01–1000 Td)

by Gregory J. Boyle, Dale L. Muccignat, Joshua R. Machacek and Robert P. McEachran

Atoms 2025, 13(10), 82; https://doi.org/10.3390/atoms13100082 - 23 Sep 2025

We report calculations for electron–radon scattering using a complex relativistic optical potential method. The energy range of this study is 0–1000 eV, with results for the elastic (total, momentum-transfer and viscosity-transfer) cross section, summed discrete electronic-state integral excitation cross sections and electron-impact ionization [...] Read more.

We report calculations for electron–radon scattering using a complex relativistic optical potential method. The energy range of this study is 0–1000 eV, with results for the elastic (total, momentum-transfer and viscosity-transfer) cross section, summed discrete electronic-state integral excitation cross sections and electron-impact ionization cross sections presented. Here, we obtain our cross sections from a single theoretical relativistic calculation. Since radon is a heavy element, a relativistic treatment is very desirable. The electron transport coefficients are subsequently calculated for reduced electric fields ranging from 0.01 to 1000 Td, using a multi-term solution of Boltzmann’s equation. Full article

► Show Figures

Figure 1

11 pages, 351 KB

Open AccessArticle

Short–Range Hard–Sphere Potential and Coulomb Interaction: Deser–Trueman Formula for Rydberg States of Exotic Atomic Systems

by Gregory S. Adkins and Ulrich D. Jentschura

Atoms 2025, 13(9), 81; https://doi.org/10.3390/atoms13090081 - 11 Sep 2025

In exotic atomic systems with hadronic constituent particles, it is notoriously difficult to estimate the strong-interaction correction to energy levels. It is well known that, due to the strength of the nuclear interaction, the problem cannot be solved using Wigner–Brillouin perturbation theory alone. [...] Read more.

In exotic atomic systems with hadronic constituent particles, it is notoriously difficult to estimate the strong-interaction correction to energy levels. It is well known that, due to the strength of the nuclear interaction, the problem cannot be solved using Wigner–Brillouin perturbation theory alone. Recently, high-angular-momentum Rydberg states of exotic atomic systems with hadronic constituents have been identified as promising candidates in the search for new physics in the low-energy sector of the Standard Model. We thus derive a generalized Deser–Trueman formula for the induced energy shift for a general hydrogenic bound state with principal quantum number n and orbital angular momentum quantum number ℓ, and we find that the energy shift is given by the formula

δ E = 2 α_{n, ℓ} β_{ℓ} {(a_{h} / a_{0})}^{2 ℓ + 1} E_{h} / n^{3}

, where

α_{n, 0} = 1

,

α_{n, ℓ} = \prod_{s = 1}^{ℓ} (s^{- 2} - n^{- 2})

,

β_{ℓ} = (2 ℓ + 1) / {[(2 ℓ + 1)!!]}^{2}

,

E_{h}

is the Hartree energy,

a_{h}

is the hadronic radius and

a_{0}

is the generalized Bohr radius. The square of the double factorial,

{[(2 ℓ + 1)!!]}^{2}

, in the denominator implies a drastic suppression of the effect for higher angular momenta. Full article

(This article belongs to the Section Nuclear Theory and Experiments)

► Show Figures

Figure 1

13 pages, 3730 KB

Open AccessArticle

IKEBANA: Data-Driven Neural-Network Predictor of Electron-Impact K-Shell Ionization Cross Sections

by Darío M. Mitnik, Claudia C. Montanari, Silvina Segui, Silvina P. Limandri, Judith A. Guzmán, Alejo C. Carreras and Jorge C. Trincavelli

Atoms 2025, 13(9), 80; https://doi.org/10.3390/atoms13090080 - 11 Sep 2025

A fully connected neural network was trained to model the K-shell ionization cross sections based on two input features: the atomic number and the incoming electron overvoltage. The training utilized a recent, updated compilation of experimental data covering elements from H to U, [...] Read more.

A fully connected neural network was trained to model the K-shell ionization cross sections based on two input features: the atomic number and the incoming electron overvoltage. The training utilized a recent, updated compilation of experimental data covering elements from H to U, and incident electron energies ranging from the threshold to relativistic values. The neural network demonstrated excellent predictive performance, compared with the experimental data, when available, and with full theoretical predictions. The developed model is provided in the ikebana code, which is openly available and requires only the user-selected atomic number and electron energy range as inputs. Full article

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

► Show Figures

Figure 1

12 pages, 2083 KB

Open AccessArticle

Theoretical Study of Spectroscopic Properties of Fe(III)(acac)₃ Under All-Electron Scalar Relativistic Effects

by Luiz C. de Miranda and Nelson H. Morgon

Atoms 2025, 13(9), 79; https://doi.org/10.3390/atoms13090079 - 11 Sep 2025

Molecular geometry, infrared (IR) vibrational frequencies, and ultraviolet–visible (UV-Vis) electronic absorption spectra of the trivalent iron tris(acetylacetonate) complex, Fe(III)(acac)₃, were computed using hybrid meta-generalized gradient approximation (meta-GGA) density functional theory (DFT). Calculations employed the Jorge double-

ζ

valence plus polarization basis [...] Read more.

Molecular geometry, infrared (IR) vibrational frequencies, and ultraviolet–visible (UV-Vis) electronic absorption spectra of the trivalent iron tris(acetylacetonate) complex, Fe(III)(acac)₃, were computed using hybrid meta-generalized gradient approximation (meta-GGA) density functional theory (DFT). Calculations employed the Jorge double-

ζ

valence plus polarization basis sets (standard DZP and relativistic DZP + DKH). Solvent effects were modeled using the SMD continuum solvation framework with acetonitrile as the dielectric medium. This charge-neutral complex exhibits predominantly ionic metal–ligand bonding character, which simplifies the computational treatment. Despite extensive DFT applications to coordination compounds, systematic benchmarks for this bidentate ligand system remain limited. The computed harmonic frequencies (

ν

) and electronic excitation energies (

λ_{\max}

) demonstrate excellent agreement with available experimental measurements. These results enable comparative analysis of IR and UV-Vis spectral features, both with and without all-electron scalar relativistic effects with the second-order Douglas–Kroll–Hess approach. Full article

(This article belongs to the Section Quantum Chemistry, Computational Chemistry and Molecular Physics)

► Show Figures

Graphical abstract

16 pages, 1203 KB

Open AccessArticle

Assessment of Absorbed Dose from a Positron Beam in Biological Tissue and Its Potential for Radiotherapy

by Andrezza O. Arêas and Maikel Y. Ballester

Atoms 2025, 13(9), 78; https://doi.org/10.3390/atoms13090078 - 10 Sep 2025

Fast-charged particles have been used in diagnosis and treatment since the 19th century. Positrons are widely used in medical imaging through positron emission tomography, but their therapeutic potential remains underexplored due to technology limitations associated with the lack of research on their effectiveness [...] Read more.

Fast-charged particles have been used in diagnosis and treatment since the 19th century. Positrons are widely used in medical imaging through positron emission tomography, but their therapeutic potential remains underexplored due to technology limitations associated with the lack of research on their effectiveness against cancer. One way to understand their behavior is by calculating absorbed dose distributions in tissue, which can be safely and realistically done using computational simulations such as the Monte Carlo Method. This study investigates the interaction of a positron beam with brain tissue and a tumor through simulations using the TOPAS software. Depth dose profiles and absolute absorbed dose values were obtained in the range of 6–24 MeV. Validation was performed using data from the water phantom with electron beams. The results showed that, at certain depths in brain tissue, the absorbed dose by positrons was higher than that of electrons under the same conditions, ranging from 57% to 463% more. These findings suggest that positrons may offer advantages over conventional electron therapy and contribute to the development of novel therapeutic approaches. Full article

► Show Figures

Figure 1

16 pages, 1119 KB

Open AccessArticle

Simulated Photoabsorption Spectra for Singly and Multiply Charged Ions

by Stephan Fritzsche, Aloka Kumar Sahoo, Lalita Sharma and Stefan Schippers

Atoms 2025, 13(9), 77; https://doi.org/10.3390/atoms13090077 - 3 Sep 2025

Simulated (or measured) photoabsorption spectra often provide the first indication of how matter interacts with light when irradiated by some radiation source. In addition to the direct, often slowly varying photoabsorption cross-section as a function of the incident photon frequency, such spectra typically [...] Read more.

Simulated (or measured) photoabsorption spectra often provide the first indication of how matter interacts with light when irradiated by some radiation source. In addition to the direct, often slowly varying photoabsorption cross-section as a function of the incident photon frequency, such spectra typically exhibit numerous resonances and edges arising from the interaction of the radiation field with the subvalence or even inner-shell electrons. Broadly speaking, these resonances reflect photoexcitation, with its subsequent fluorescence, or the autoionization of bound electrons. Here, a (relativistic) cascade model is developed for estimating the photoabsorption of (many) atoms and multiply charged ions with a complex shell structure across the periodic table. This model helps distinguish between level- and shell-resolved, as well as total photoabsorption, cross-sections, starting from admixtures of selected initial-level populations. Examples are shown for the photoabsorption of C⁺ ions near the 1s − 2p excitation threshold and for Xe²⁺ ions in the photon energy range from 10 to 200 eV. While the accuracy and resolution of the predicted photoabsortion spectra remain limited due to the additive treatment of resonances and because of missing electronic correlations in the representation of the levels involved, the present implementation is suitable for ions with quite different open-shell structures and may support smart surveys of resonances along different isoelectronic sequences. Full article

► Show Figures

Figure 1

10 pages, 784 KB

Open AccessArticle

Larmor Time for Trapezoidal Barrier

by Tengfei Li and Zhi Xiao

Atoms 2025, 13(9), 76; https://doi.org/10.3390/atoms13090076 - 29 Aug 2025

In this paper, we explore the Larmor time for three types of trapezoidal barriers, and we find consistent results between the traditionally defined Larmor time and a newly defined one. We confirm that the transmission Larmor time for the trapezoidal barriers also satisfies [...] Read more.

In this paper, we explore the Larmor time for three types of trapezoidal barriers, and we find consistent results between the traditionally defined Larmor time and a newly defined one. We confirm that the transmission Larmor time for the trapezoidal barriers also satisfies certain properties of mirror-symmetric barriers. Consistent with our expectations, we also find that: 1. as the barrier height increases, the peak of the Larmor time shifts to the right (higher energy); and 2. as the barrier width increases, the peak becomes larger in coincidence with the classical expectation that a particle needs more time to cross a longer path of the same height/inclination. Full article

► Show Figures

Figure 1

9 pages, 549 KB

Open AccessArticle

Interfacing the B-Spline R-Matrix and R-Matrix with Time Dependence Computer Codes: An Update

by Juan C. Del Valle, Aaron T. Bondy, Soumyajit Saha, Kathryn R. Hamilton and Klaus Bartschat

Atoms 2025, 13(9), 75; https://doi.org/10.3390/atoms13090075 - 29 Aug 2025

As a continuation of Schneider et al., Atoms 2022 10, 26, we report recent progress in the development and deployment of the interface between the computational codes B-Spline R-matrix (BSR) and R-Matrix with Time dependence (RMT). These advances have been achieved within [...] Read more.

As a continuation of Schneider et al., Atoms 2022 10, 26, we report recent progress in the development and deployment of the interface between the computational codes B-Spline R-matrix (BSR) and R-Matrix with Time dependence (RMT). These advances have been achieved within the context of the

L S

-coupling scheme. In its current state, the interface handles atomic target states described by single configurations and supports the Fano–Racah phase convention, as required by RMT. As first example of an application, we use the interface to investigate multiphoton single ionization of helium exposed to a linearly polarized laser field with wavelengths between 280 and 316 nm and a peak intensity of

3 \times 10^{14}

W/cm². As a second example, we consider high-order harmonic generation (HHG) in carbon, driven by an intense 30-cycle laser field at 800 nm and a peak intensity of

1 \times 10^{12}

W/cm². Full article

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

► Show Figures

Figure 1

12 pages, 1240 KB

Open AccessArticle

State-Selective Differential Cross Sections for Single-Electron Capture in Slow He⁺–He Collisions

by Shucheng Cui, Kaizhao Lin, Dadi Xing, Ling Liu, Dongmei Zhao, Dalong Guo, Yong Gao, Shaofeng Zhang, Yong Wu, Chenzhong Dong, Xiaolong Zhu and Xinwen Ma

Atoms 2025, 13(9), 74; https://doi.org/10.3390/atoms13090074 - 28 Aug 2025

A combined experimental and theoretical study is carried out on the single-electron capture process in He⁺–He collisions at energies ranging from 0.5 keV/u to 5 keV/u. Using cold target recoil ion momentum spectroscopy, we obtain state-selective cross sections and angular differential [...] Read more.

A combined experimental and theoretical study is carried out on the single-electron capture process in He⁺–He collisions at energies ranging from 0.5 keV/u to 5 keV/u. Using cold target recoil ion momentum spectroscopy, we obtain state-selective cross sections and angular differential cross sections. Within the entire studied energy range, the dominant channel is the electron captured into the ground-state, and the relative contribution of the dominant channel shows a decreasing trend with increasing energy. The angular differential cross sections of ground-state capture exhibit obvious oscillatory structures. To understand the oscillatory structures of the differential cross sections, we also performed theoretical calculations using the two-center atomic orbital close-coupling method, which well reproduced the oscillatory structures. The results indicate that these structures are strongly correlated to the oscillatory structures of the impact parameter dependence of electron probability. Full article

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

► Show Figures

Figure 1

12 pages, 320 KB

Open AccessArticle

Inner Products of Spherical Tensor Operators: A Late Chapter of Racah Algebra

by Peter Uylings

Atoms 2025, 13(8), 73; https://doi.org/10.3390/atoms13080073 - 19 Aug 2025

Inner products of spherical tensor operators have been used since the early eighties to define orthogonal operators. However, the basic theory and properties are largely missing in the literature. An inner product in any configuration is directly proportional to the inner product taken [...] Read more.

Inner products of spherical tensor operators have been used since the early eighties to define orthogonal operators. However, the basic theory and properties are largely missing in the literature. An inner product in any configuration is directly proportional to the inner product taken in the most basic configuration in which it can occur. The formula for the proportionality factor in question is presented for the first time. This allows the inner products in and between arbitrary configurations to be calculated in advance. In addition, inner products are shown to be independent of the coupling scheme used to construct the state functions. Applications such as the orthogonal operator method and projections of ab initio calculations check for the completeness of the used basis of operators and, importantly, check the matrix elements in any arbitrary configuration, as discussed and illustrated with examples. Closed formulae for the inner products of the well-known Slater and spin–orbit operators are given. Full article

15 pages, 628 KB

Open AccessArticle

Accurate Nonrelativistic Energy Calculations for Helium 1snp^1,3P (n = 2 to 27) States via Correlated B-Spline Basis Functions

by Jing Chi, Hao Fang, Yong-Hui Zhang, Xiao-Qiu Qi, Li-Yan Tang and Ting-Yun Shi

Atoms 2025, 13(8), 72; https://doi.org/10.3390/atoms13080072 - 4 Aug 2025

Rydberg atoms play a crucial role in testing atomic structure theory, quantum computing and simulation. Measurements of transition frequencies from the

2^{1, 3} S

states to Rydberg

{}^{1, 3}P

states have reached a precision of several kHz, which poses [...] Read more.

Rydberg atoms play a crucial role in testing atomic structure theory, quantum computing and simulation. Measurements of transition frequencies from the

2^{1, 3} S

states to Rydberg

{}^{1, 3}P

states have reached a precision of several kHz, which poses significant challenges for theoretical calculations, since the accuracy of variational energy calculations decreases rapidly with increasing principal quantum number n. Recently the complex “triple” Hylleraas basis was employed to attain the ionization energy of helium

24 {}^{1}P

state with high accuracy. Different from it, we extended the correlated B-spline basis functions (C-BSBFs) to calculate the Rydberg states of helium. The nonrelativistic energies of

1 s n p

{}^{1, 3}P

states up to

n = 27

achieve at least 14 significant digits using a unified basis set, thereby greatly reducing the complexity of the optimization process. Results of geometric structure parameters and cusp conditions were presented as well. Both the global operator and direct calculation methods are employed and cross-checked for contact potentials. This C-BSBF method not only obtains high-accuracy energies across all studied levels but also confirms the effectiveness of the C-BSBFs in depicting long-range and short-range correlation effects, laying a solid foundation for future high-accuracy Rydberg-state calculations with relativistic and QED corrections included in helium atom and low-Z helium-like ions. Full article

(This article belongs to the Special Issue Atom and Plasma Spectroscopy)

► Show Figures

Figure 1

7 pages, 1017 KB

Open AccessCommunication

Observing the Ionization of Metastable States of Sn¹⁴⁺ in an Electron Beam Ion Trap

by Qi Guo, Zhaoying Chen, Fangshi Jia, Wenhao Xia, Xiaobin Ding, Jun Xiao, Yaming Zou and Ke Yao

Atoms 2025, 13(8), 71; https://doi.org/10.3390/atoms13080071 - 1 Aug 2025

This study investigates the ionization balance of Sn ions in an electron beam ion trap (EBIT). Highly charged Sn ions are produced via collisions with a quasi-monochromatic electron beam, and the charge state distribution is analyzed using a Wien filter. Significant Sn¹⁵⁺ [...] Read more.

This study investigates the ionization balance of Sn ions in an electron beam ion trap (EBIT). Highly charged Sn ions are produced via collisions with a quasi-monochromatic electron beam, and the charge state distribution is analyzed using a Wien filter. Significant Sn¹⁵⁺ production occurs at electron energies below the ionization potential of Sn¹⁴⁺ (379 eV). Calculations attribute this to electron-impact ionization from metastable Sn¹⁴⁺ states. Full article

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

► Show Figures

Figure 1

13 pages, 359 KB

Open AccessReview

Numerical Methods for the Time-Dependent Schrödinger Equation: Beyond Short-Time Propagators

by Ryan Schneider and Heman Gharibnejad

Atoms 2025, 13(8), 70; https://doi.org/10.3390/atoms13080070 - 28 Jul 2025

This article reviews several numerical methods for the time-dependent Schrödinger Equation (TDSE). We consider both the most commonly used approach—short-time propagation, which solves the TDSE by assuming that the Hamiltonian is time-independent over sufficiently small (time) intervals—as well as a number of higher-order [...] Read more.

This article reviews several numerical methods for the time-dependent Schrödinger Equation (TDSE). We consider both the most commonly used approach—short-time propagation, which solves the TDSE by assuming that the Hamiltonian is time-independent over sufficiently small (time) intervals—as well as a number of higher-order alternatives. Our goal is to dispel the notion that the latter are too computationally demanding for practical use. To that end, we cover methods whose numerical building blocks are shared by short-time propagators or can be handled by standard libraries. Moreover, we make the case that these methods are best positioned to take advantage of parallel computing environments. One of the alternatives considered is a “double DVR” solver, which applies an expansion in a product basis of functions in space and time to obtain a solution (over all space and at multiple time points simultaneously) with a single linear system solve. To our knowledge, and despite its simplicity, this approach has not previously been applied to the TDSE. Full article

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

► Show Figures

Figure 1

19 pages, 2243 KB

Open AccessArticle

Theoretical Calculation of Ground and Electronically Excited States of MgRb⁺ and SrRb⁺ Molecular Ions: Electronic Structure and Prospects of Photo-Association

by Mohamed Farjallah, Hela Ladjimi, Wissem Zrafi and Hamid Berriche

Atoms 2025, 13(8), 69; https://doi.org/10.3390/atoms13080069 - 25 Jul 2025

In this work, a comprehensive theoretical investigation is carried out to explore the electronic and spectroscopic properties of selected diatomic molecular ions MgRb⁺ and SrRb⁺. Using high-level ab initio calculations based on a pseudopotential approach, along with large Gaussian basis [...] Read more.

In this work, a comprehensive theoretical investigation is carried out to explore the electronic and spectroscopic properties of selected diatomic molecular ions MgRb⁺ and SrRb⁺. Using high-level ab initio calculations based on a pseudopotential approach, along with large Gaussian basis sets and full valence configuration interaction (FCI), we accurately determine adiabatic potential energy curves, spectroscopic constants, transition dipole moments (TDMs), and permanent electric dipole moments (PDMs). To deepen our understanding of these systems, we calculate radiative lifetimes for vibrational levels in both ground and low-lying excited electronic states. This includes evaluating spontaneous and stimulated emission rates, as well as the effects of blackbody radiation. We also compute Franck–Condon factors and analyze photoassociation processes for both ions. Furthermore, to explore low-energy collisional dynamics, we investigate elastic scattering in the first excited states (2¹Σ⁺) describing the collision between the Ra atom and Mg⁺ or Sr⁺ ions. Our findings provide detailed insights into the theoretical electronic structure of these molecular ions, paving the way for future experimental studies in the field of cold and ultracold molecular ion physics. Full article

(This article belongs to the Section Quantum Chemistry, Computational Chemistry and Molecular Physics)

► Show Figures

Figure 1

16 pages, 1681 KB

Open AccessArticle

Thermal–Condensate Collisional Effects on Atomic Josephson Junction Dynamics

by Klejdja Xhani and Nick P. Proukakis

Atoms 2025, 13(8), 68; https://doi.org/10.3390/atoms13080068 - 22 Jul 2025

We investigate how collisional interactions between the condensate and the thermal cloud influence the distinct dynamical regimes (Josephson plasma, phase-slip-induced dissipative regime, and macroscopic quantum self-trapping) emerging in ultracold atomic Josephson junctions at non-zero subcritical temperatures. Specifically, we discuss how the self-consistent dynamical [...] Read more.

We investigate how collisional interactions between the condensate and the thermal cloud influence the distinct dynamical regimes (Josephson plasma, phase-slip-induced dissipative regime, and macroscopic quantum self-trapping) emerging in ultracold atomic Josephson junctions at non-zero subcritical temperatures. Specifically, we discuss how the self-consistent dynamical inclusion of collisional processes facilitating the exchange of particles between the condensate and the thermal cloud impacts both the condensate and the thermal currents, demonstrating that their relative importance depends on the system’s dynamical regime. Our study is performed within the full context of the Zaremba–Nikuni–Griffin (ZNG) formalism, which couples a dissipative Gross–Pitaevskii equation for the condensate dynamics to a quantum Boltzmann equation with collisional terms for the thermal cloud. In the Josephson plasma oscillation and vortex-induced dissipative regimes, collisions markedly alter dynamics at intermediate-to-high temperatures, amplifying damping in the condensate imbalance mode and inducing measurable frequency shifts. In the self-trapping regime, collisions destabilize the system even at low temperatures, prompting a transition to Josephson-like dynamics on a temperature-dependent timescale. Our results show the interplay between coherence, dissipation, and thermal effects in a Bose–Einstein condensate at a finite temperature, providing a framework for tailoring Josephson junction dynamics in experimentally accessible regimes. Full article

(This article belongs to the Special Issue Quantum Technologies with Ultracold Atoms)

► Show Figures

Figure 1

12 pages, 1305 KB

Open AccessArticle

Monte Carlo FLUKA Simulation of Gamma Backscattering for Rebar Detection in Reinforced Concrete with Basaltic Aggregates

by Alexandre Osni Gral Iori and Emerson Mario Boldo

Atoms 2025, 13(7), 67; https://doi.org/10.3390/atoms13070067 - 9 Jul 2025

Compton backscattering is a versatile non-destructive technique for material characterization and structural evaluation in reinforced concrete. This methodology enables a single-sided inspection of large structures—which is particularly useful where only one side of the material is accessible for examination—is relatively inexpensive, and can [...] Read more.

Compton backscattering is a versatile non-destructive technique for material characterization and structural evaluation in reinforced concrete. This methodology enables a single-sided inspection of large structures—which is particularly useful where only one side of the material is accessible for examination—is relatively inexpensive, and can be made portable for field applications. This study aims to assess the influence of basaltic coarse aggregates on the accurate localization and dimensioning of rebar in reinforced concrete using the gamma-ray Compton backscattering technique at two distinct incident photon energies—59.5 keV and 1170 keV. The analysis was performed through Monte Carlo simulations using the FLUKA code, providing insights into the feasibility and limitations of this non-destructive method for structural evaluation. Both photon energies successfully detected the rebar embedded at a 3 cm depth in mortar, achieving a good spatial resolution and contrast, despite the presence of a significant amount of iron oxide within the aggregate. Among the evaluated sources, ⁶⁰Co yielded the highest contrast and count values, demonstrating its potential for rebar detection at greater depths within concrete structures. The single-sided Compton scattering technique proved to be effective for the investigated application and presents a promising alternative for the non-destructive assessment of real-world reinforced concrete structures. Full article

(This article belongs to the Section Nuclear Theory and Experiments)

► Show Figures

Figure 1

24 pages, 1467 KB

Open AccessArticle

Introducing Machine Learning in Teaching Quantum Mechanics

by M. K. Pawelkiewicz, Filippo Gatti, Didier Clouteau, Viatcheslav Kokoouline and Mehdi Adrien Ayouz

Atoms 2025, 13(7), 66; https://doi.org/10.3390/atoms13070066 - 8 Jul 2025

In this article, we describe an approach to teaching introductory quantum mechanics and machine learning techniques. This approach combines several key concepts from both fields. Specifically, it demonstrates solving the Schrödinger equation using the discrete-variable representation (DVR) technique, as well as the architecture [...] Read more.

In this article, we describe an approach to teaching introductory quantum mechanics and machine learning techniques. This approach combines several key concepts from both fields. Specifically, it demonstrates solving the Schrödinger equation using the discrete-variable representation (DVR) technique, as well as the architecture and training of neural network models. To illustrate this approach, a Python-based Jupyter notebook is developed. This notebook can be used for self-learning or for learning with an instructor. Furthermore, it can serve as a toolbox for demonstrating individual concepts in quantum mechanics and machine learning and for conducting small research projects in these areas. Full article

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

► Show Figures

Figure 1

10 pages, 14429 KB

Open AccessArticle

Polarization Reconstruction Based on Monte Carlo Simulations for a Compton Polarimeter

by Tobias Over-Winter, Wilko Middents, Günter Weber and Thomas Stöhlker

Atoms 2025, 13(7), 65; https://doi.org/10.3390/atoms13070065 - 4 Jul 2025

State-of-the-art 2D sensitive semiconductor detectors developed within the SPARC collaboration can be utilized as dedicated Compton polarimeters in the hard X-ray regime. We report on the technique of Compton polarimetry utilizing such a detector and present a method to determine the linear polarization [...] Read more.

State-of-the-art 2D sensitive semiconductor detectors developed within the SPARC collaboration can be utilized as dedicated Compton polarimeters in the hard X-ray regime. We report on the technique of Compton polarimetry utilizing such a detector and present a method to determine the linear polarization of an analyzed hard X-ray beam by means of Monte-Carlo-simulated data sets. Full article

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

► Show Figures

Figure 1

More Articles...

Submit to Atoms Review for Atoms

Journal Menu

Journal Browser

► Journal Browser

Highly Accessed Articles

View More...

Latest Books

More Books and Reprints...

E-Mail Alert

News

1 October 2025
2024 MDPI Top 1000 Reviewers

2 October 2025
MDPI INSIGHTS: The CEO's Letter #27 - OASPA 2025, COUNTER 5.1, UK Summit in London, MDPI at the Italian Senate

30 September 2025
Nobel Prize — The Science Behind the Prize

More News & Announcements...

Topics

Propose a Topic

Topic in Atoms, Crystals, Molecules, Organics, Symmetry, Inorganics

Advances in Molecular Symmetry and Chirality Research Topic Editors: Ralph N. Salvatore, Guzman Gil-Ramirez
Deadline: 31 March 2026

Conferences

Propose a Conference Collaboration

29–30 January 2026 The 1st International Online Conference on Atoms (IOCAT 2026)

More Conferences...

Special Issues

Propose a Special Issue

Special Issue in Atoms

Many-Particle Dynamics in Collisions of Electrons, Positrons and Photons, 2nd Edition Guest Editors: Dhanoj Gupta, Paresh Modak, Suvam Singh
Deadline: 15 October 2025

Special Issue in Atoms

Advances in and Prospects for Matter Wave Interferometry: Second Edition Guest Editors: Tim Kovachy, Selim Shahriar, Andrew Geraci
Deadline: 30 November 2025

Special Issue in Atoms

Quantum Technologies with Cold Atoms Guest Editor: Jianing Han
Deadline: 15 December 2025

Special Issue in Atoms

Interactions of Positrons with Matter and Radiation: Second Edition Guest Editor: Anand Bhatia
Deadline: 31 December 2025

More Special Issues

Back to TopTop