The European Physical Journal B最新文献

{"title":"Optical high harmonic generation in Dirac materials","authors":"S. Rakhmanov,&nbsp;K. Matchonov,&nbsp;H. Yusupov,&nbsp;K. Nasriddinov,&nbsp;D. Matrasulov","doi":"10.1140/epjb/s10051-025-00885-7","DOIUrl":"10.1140/epjb/s10051-025-00885-7","url":null,"abstract":"<p>We study high-order harmonic generation by optically driven one- and two-dimensional hydrogen-like atoms formed by Coulomb impurities in graphene. The time-dependent Dirac equations with Coulomb plus time-periodic monochromatic field potentials are solved for both cases. Such characteristics of the optical high harmonic generation, as average dipole moment and high harmonic generation spectra, are computed. A sketch for table-top experimental realization of the considered models is proposed.</p>","PeriodicalId":787,"journal":{"name":"The European Physical Journal B","volume":"98 2","pages":""},"PeriodicalIF":1.6,"publicationDate":"2025-02-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143465965","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Influence of vertical throughflow on the linear and nonlinear stability analyses of Rayleigh–Bénard convection in a biviscous Bingham fluid saturating a porous medium","authors":"Pankaj Barman,&nbsp;D. Srinivasachrya,&nbsp;Dipak Barman","doi":"10.1140/epjb/s10051-025-00884-8","DOIUrl":"10.1140/epjb/s10051-025-00884-8","url":null,"abstract":"<p>This article aims to investigate the influence of vertical throughflow on the stability analysis of a biviscous Bingham fluid-saturated horizontal porous layer. Specifically, both linear and nonlinear stability thresholds are examined. The Darcy–Brinkman law is employed to formulate the momentum equation for the system. In this study, all three types of boundary conditions are considered: rigid-rigid, rigid-free, and free-free. The well-known energy method is applied to conduct the nonlinear stability analysis, while the linear stability analysis is carried out using the normal mode approach. The resultant eigenvalue problems are solved using the <i>bvp4c</i>-scheme in MATLAB 2022(a). The critical Rayleigh number and the corresponding wave numbers are obtained numerically by minimizing the neutral stability curves for both theories, and are calculated for the specified values of the flow-governing parameters, with the results presented graphically. It is observed that an increase in the Péclet number (vertical throughflow) delays the onset of convection, whereas an increase in the biviscous Bingham fluid parameter accelerates the onset of convection.</p>","PeriodicalId":787,"journal":{"name":"The European Physical Journal B","volume":"98 2","pages":""},"PeriodicalIF":1.6,"publicationDate":"2025-02-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143455403","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Impact of rare-earth doping on tin disulfide for photocatalytic applications: a first principles insight","authors":"Mohammed Mjahed,&nbsp;Hicham Bouda,&nbsp;El Mostafa Benchafia,&nbsp;El Mehdi Salmani,&nbsp;Hamid Ez-Zahraouy,&nbsp;Abdelilah Benyoussef","doi":"10.1140/epjb/s10051-025-00874-w","DOIUrl":"10.1140/epjb/s10051-025-00874-w","url":null,"abstract":"<p>The optoelectronic and photocatalytic properties of rare-earth components (RE<span>(=)</span> Ce, La, and Sm) incorporated into the <span>(hbox {SnS}_2)</span> structure were investigated using first principles simulations. The TB-mBJ (Tran–Blaha modified Becke–Johnson) approach was used to explore several novel properties. The observed electronic band gap energy of pure <span>(hbox {SnS}_2)</span> is <span>(E_g = 2.4)</span> eV, which is in good agreement with the reported experimental value of <span>(E_g = 2.44)</span> eV. Results show that doping <span>(hbox {SnS}_2)</span> with RE elements at a concentration of 6.25% significantly reduces the electronic band gap compared to pristine <span>(hbox {SnS}_2)</span>. This reduction can be attributed to the smaller ionic radii of <span>(hbox {Ce}^{3+})</span>, <span>(hbox {La}^{3+})</span>, and <span>(hbox {Sm}^{3+})</span> ions, as well as the appearance of new states hybridized by RE-4f within the band gap, leading to a remarkable enhancement of the absorption spectra in the visible light range. Additionally, the calculated edge positions of the conduction band minimum (CBM) and the valence band maximum (VBM) relative to the normal hydrogen electrode (NHE) for both pristine and RE-doped <span>(hbox {SnS}_2)</span> are optimal for water splitting. Consequently, doping <span>(hbox {SnS}_2)</span> with rare-earth elements appears to be a promising strategy for enhancing its photocatalytic activity in the visible light spectrum.</p>","PeriodicalId":787,"journal":{"name":"The European Physical Journal B","volume":"98 2","pages":""},"PeriodicalIF":1.6,"publicationDate":"2025-02-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143455456","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Local statistical moments to capture Kramers–Moyal coefficients","authors":"Christian Wiedemann,&nbsp;Matthias Wächter,&nbsp;Jan A. Freund,&nbsp;Joachim Peinke","doi":"10.1140/epjb/s10051-025-00883-9","DOIUrl":"10.1140/epjb/s10051-025-00883-9","url":null,"abstract":"<p>This study introduces an innovative local statistical moment approach for estimating Kramers–Moyal coefficients, effectively bridging the gap between nonparametric and parametric methodologies. These coefficients play a crucial role in characterizing stochastic processes. Our proposed approach provides a versatile framework for localized coefficient estimation, combining the flexibility of nonparametric methods with the interpretability of global parametric approaches. We showcase the efficacy of our approach through use cases involving both stationary and non-stationary time series analysis. Additionally, we demonstrate its applicability to real-world complex systems, specifically in the energy conversion process analysis of a wind turbine.</p>","PeriodicalId":787,"journal":{"name":"The European Physical Journal B","volume":"98 2","pages":""},"PeriodicalIF":1.6,"publicationDate":"2025-02-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1140/epjb/s10051-025-00883-9.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143455404","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Structural and energetic stability of the lowest equilibrium structures of water clusters","authors":"Vishwa K. Bhatt,&nbsp;Sajeev S. Chacko,&nbsp;Nitinkumar M. Bijewar,&nbsp;Balasaheb J. Nagare","doi":"10.1140/epjb/s10051-025-00881-x","DOIUrl":"10.1140/epjb/s10051-025-00881-x","url":null,"abstract":"<div><p>Water molecules with their hydrogen bonding capability, exhibit exceptional properties in the bulk as well as in cluster form. In the present work, we study the size-dependent trends in the structure, energetics, bonding, ionisation potential, fragmentation pattern, and optical properties of water clusters in the size range of <i>n</i> = 2–20, and an interplay between them. We have extensively searched for the lowest energy structures of the water clusters using the artificial bee colony algorithm, optimised them first with the classical force field TIP4P and then relaxed at least 10 lowest energy structures using density functional theory. We have found new lowest energy structures for all the sizes as against the ones reported earlier. The structures and stability of water clusters are primarily dictated by the H-bond network. However, we found the weak van der Waals interactions also play a crucial role in stabilising the clusters giving them unique characteristics. Some of the clusters such as those with <span>(n=4, 8, 10, 12)</span> and 15 molecules were structurally symmetric, yet a close analysis of various properties reveals that the clusters with <span>(n=4, 8, 12, 14)</span> and 19 molecules are more stable than others. Spherical or nearly spherical clusters were found to be the most stable, corroborated by the shape deformation parameters and the fragmentation pattern, which indicated a higher likelihood of forming fragments of sizes <span>(n=4, 8, 12, 14)</span>, and 16. A blueshift of the H-O-H vibrational modes and a redshift of the O–H stretching modes is seen for most clusters. Such characteristics in the vibrational spectra is associated with an increase in the H-bond strength which is seen to increase with size of the cluster. Large optical band gaps for <span>(n=4, 8, 12)</span> and 16 along with blueshifts in optical spectra implies these clusters to be chemically more stable than others.</p></div>","PeriodicalId":787,"journal":{"name":"The European Physical Journal B","volume":"98 2","pages":""},"PeriodicalIF":1.6,"publicationDate":"2025-02-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143438715","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Synthesis, structural characterization, and electrochemical properties of MgNiP2O7 for energy storage applications","authors":"Youssef Ghandi,&nbsp;Siham El Mazouzi,&nbsp;Chaimaa Moukhfi,&nbsp;Hassan Mabrak,&nbsp;Ali Zourif,&nbsp;Rachid Fakhreddine,&nbsp;Malika Tridane,&nbsp;Said Belaaouad","doi":"10.1140/epjb/s10051-025-00879-5","DOIUrl":"10.1140/epjb/s10051-025-00879-5","url":null,"abstract":"<div><p>This study investigates the structural, optical, and electrochemical properties of MgNiP₂O₇, a promising material for energy storage and catalysis applications. The compound was synthesized using a sol–gel method and characterized through X-ray diffraction, Fourier-transform infrared spectroscopy, and UV–visible spectroscopy. X-ray analysis confirmed a monoclinic crystal structure with space group P21/c. Optical studies revealed two distinct band gap energies at 1.6 eV and 2.66 eV, indicating potential for optoelectronic applications. Electrochemical characterization, including cyclic voltammetry, electrochemical impedance spectroscopy, and chronoamperometry, enhanced electrocatalytic activity, particularly for the oxygen reduction reaction. The material exhibited high current density and stable performance over time, suggesting its suitability for energy storage systems such as batteries and fuel cells. These findings highlight the multifunctional nature of MgNiP₂O₇ and its potential significance in developing sustainable energy technologies and environmental applications.</p><h3>Graphical abstract</h3><div><figure><div><div><picture><source><img></source></picture></div></div></figure></div></div>","PeriodicalId":787,"journal":{"name":"The European Physical Journal B","volume":"98 2","pages":""},"PeriodicalIF":1.6,"publicationDate":"2025-02-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143430703","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Role of correlation and spin-orbit coupling in (text {LuB}_{4}): a first principles study","authors":"Ismail Sk,&nbsp;Joydeep Chatterjee,&nbsp;Arghya Taraphder,&nbsp;Nandan Pakhira","doi":"10.1140/epjb/s10051-025-00878-6","DOIUrl":"10.1140/epjb/s10051-025-00878-6","url":null,"abstract":"<p>The recent observation of magnetization plateaus in rare-earth metallic tetraborides has drawn considerable attention to this class of materials. In this work, we investigate the electronic structure of one such canonical system, <span>(text {LuB}_{4})</span>, using first-principles density functional theory together with Coulomb correlation and spin-orbit coupling (SOC). The electronic band structures show that <span>(text {LuB}_{4})</span> is a non-magnetic correlated metal with a completely filled 4<i>f</i> shell. The projected density of states (DOS) shows a continuum at the Fermi level (FL), arising mainly from hybridized Lu <i>d</i> and B <i>p</i> orbitals, along with some discrete peaks well separated from the continuum. These peaks arise mainly due to core-level Lu <i>s</i>, <i>p</i> and 4<i>f</i> atomic orbitals. Upon inclusion of SOC, the discrete peak arising due to Lu <i>p</i> is split into two peaks with <span>(j = 1/2)</span>, <span>(j = 3/2)</span> while the peak arising from Lu 4<i>f</i> orbitals splits into two peaks with <span>(j = 5/2)</span> and    <span>(j = 7/2)</span>. These peaks will give rise to multiplet structure in core-level X-ray photo-emission spectroscopy and resonant inelastic X-ray scattering. Inclusion of correlation effects pushes the Lu 4<i>f</i> peak away from the FL, while the qualitative features remain intact. The present calculations will lead to an effective low-energy model for future investigation of transport and other properties.</p>","PeriodicalId":787,"journal":{"name":"The European Physical Journal B","volume":"98 2","pages":""},"PeriodicalIF":1.6,"publicationDate":"2025-02-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143423441","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Synthesis, experimental and computational approach to optical, electronic and structural studies of N-acetyl l-alanine crystal","authors":"P. Krishnamoorthy,&nbsp;K. Premlatha,&nbsp;T. K. Arumugam,&nbsp;S. Seshadri,&nbsp;N. R. Rajagopalan","doi":"10.1140/epjb/s10051-025-00873-x","DOIUrl":"10.1140/epjb/s10051-025-00873-x","url":null,"abstract":"<div><p>Single-crystal <i>N</i>-acetyl-<span>l</span>-alanine (NALA), a semi-organic crystal, has been synthesized by slow evaporation growth technique in aqueous medium. An experimental study proves that it has the space group of P2₁2₁2 and orthorhombic crystal system. The unit-cell parameters of NALA crystal were identified using single-crystal XRD analysis. UV–vis analysis has been used to find out the cut-off wavelength of the crystal. The calculated Urbach energy and the related optical constant values support the non-linear optics (NLO) nature of NALA crystal. SEM and EDAX experiments were carried out to find the surface and elemental characteristics of the NALA crystal. Vickers micro-hardness studies have been utilized to probe the mechanical stability of the crystal. Kurtz–Perry Simple Harmonic Generation (SHG) study has suggested 1.4 times greater NLO efficiency of NALA crystal than that of standard KDP. Thermal stability of the crystal is demonstrated by TGA and DTA analysis. Glass transition (<i>T</i>_g) temperature is achieved through DSC analysis. Coats–Redfern method has been used to explain the thermodynamic parameters. The theoretical calculation done by density functional theory (DFT) and the computed values of polarizability calculations of NALA are compared and justifiable with the standard values. Polarizability and first-order hyperpolarizability (both static and dynamic) are calculated to see the potential application in non-linear optics and it is observed that the values are found to be 2.7 times greater than those of prototype at the same theoretical functional. The frontier study of HOMO–LUMO is used to interpret the global chemical molecular descriptors and indicate the applicability of the NALA crystal toward optical device fabrication.</p><h3>Graphical Abstract</h3><p>Hydrogen bonding graphical extract</p><div><figure><div><div><picture><source><img></source></picture></div></div></figure></div></div>","PeriodicalId":787,"journal":{"name":"The European Physical Journal B","volume":"98 2","pages":""},"PeriodicalIF":1.6,"publicationDate":"2025-02-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143423443","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Photoacoustic dynamics in microtemperature semiconductor media with variable thermal conductivity and nonlocal effects","authors":"Tarek E. I. Nassar,&nbsp;A. M. S. Mahdy,&nbsp;Kh. Lotfy","doi":"10.1140/epjb/s10051-025-00877-7","DOIUrl":"10.1140/epjb/s10051-025-00877-7","url":null,"abstract":"<div><p>The study investigates the photoacoustic pressure effects on microtemperature distributions within a nanostructured (nonlocal) elastic semiconductor medium, where thermal conductivity is considered variable. Photoacoustic phenomena, which involve the generation of acoustic (elastic) waves due to the absorption of modulated light, play a pivotal role in heat transfer dynamics at the nanoscale. The interaction between photoacoustic pressure, plasma waves, and thermal waves influences localized temperature variations in semiconductor nanostructures. The variable thermal conductivity, which accounts for temperature dependence and nanoscale effects, adds complexity to the heat diffusion process. Using mathematical modeling and numerical simulations, the photoacoustic pressure-driven thermal response is analyzed in one dimension (1D) under different excitation frequencies and thermal conductivity profiles. Results show that the variable thermal conductivity significantly affects the propagation of thermal waves, acoustic pressure, elastic, mechanical, microtemperature, and carrier density diffusion, leading to enhanced heat confinement or dispersion depending on material properties and operating conditions. The findings have implications for the design of semiconductor devices where thermal management is critical, such as in photodetectors, microelectronic systems, and optoelectronic devices. This research advances the understanding of nanoscale heat transfer mechanisms in semiconductors under photoacoustic excitation and provides insight into optimizing thermal performance in nanostructured materials.</p><h3>Graphical abstract</h3>\u0000<div><figure><div><div><picture><source><img></source></picture></div></div></figure></div></div>","PeriodicalId":787,"journal":{"name":"The European Physical Journal B","volume":"98 2","pages":""},"PeriodicalIF":1.6,"publicationDate":"2025-02-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143423398","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Subtle modulation of the nonlinear optical properties of GaAs quantum dot by the interplay between noise and impurity extension","authors":"Bhaskar Bhakti,&nbsp;Swarnab Datta,&nbsp;Anuja Ghosh,&nbsp;Manas Ghosh","doi":"10.1140/epjb/s10051-025-00880-y","DOIUrl":"10.1140/epjb/s10051-025-00880-y","url":null,"abstract":"<p>Current enquiry puts emphasis on unveiling the role of subtle interplay between <i>spatial dissemination of impurity</i> and <i>Gaussian white noise</i> on a few <i>nonlinear optical (NLO)</i> properties of the <i>doped GaAs quantum dot (QD)</i>. The NLO properties include <i>group index (GI)</i>, <i>DC-Kerr effect (DCKE)</i>, <i>electro-absorption coefficient (EAC)</i> and <i>optical gain (OG)</i>. GI, DCKE and EAC manifest red-shift with the enhancement of the spatial width of the dopant, both including and excluding noise. In case of OG, however, both with and without noise, the peak shift becomes non-uniform as the dopant stretch increases. The interplay between noise and the impurity spread becomes different for additive and multiplicative noise. Delicate modulation of impurity spread, in combination with the mode of introduction of noise, can control the regimes of fast and slow light in the system, the magnitudes of DCKE and EAC and can even cause maximization of OG and the current density in the vicinity of some typical spatial spread of the dopant.</p>","PeriodicalId":787,"journal":{"name":"The European Physical Journal B","volume":"98 2","pages":""},"PeriodicalIF":1.6,"publicationDate":"2025-02-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143404113","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}