bluuebunny/crossref_metadata_2025_split huggingface dataset:
Probing the cosmological principle using the slope of log N-log S relationship for quasars
Authors: Panwar Mohit , Jain Pankaj 
Published: June 2024

Abstract
We study the dipole signal in the slope x of the log N–log S relationship for quasars using the CatWISE2020 catalog of infrared sources. Here N is the number of sources with flux density greater than S. The slope is extracted by using a maximized log-likelihood method as well as Bayesian analysis. We obtain the value x = 1.579 ± 0.001 for a quasar sample of 1355352 sources. We extract the dipole signal in this parameter by employing χ
2 minimization, assuming a sky model of x up to the quadrupole term. We find that the dipole amplitude |D| is 0.005 ± 0.002 and dipole direction (l, b) in Galactic coordinate system equal to (201.50° ± 27.87°, -29.37° ± 19.86°). The direction of dipole anisotropy is found to be very close to the hemispherical power asymmetry (l, b)=(221°,-27°) in the Cosmic Microwave Background (CMB). The dipole signal is also extracted using Bayesian analysis and found to be in good agreement with that obtained using χ
2 minimization. We also obtain a signal of quadrupole anisotropy which is found to be correlated with the ecliptic poles and can be attributed to ecliptic bias.
Complete analysis of hyperentangled Bell state in three degrees of freedom using Kerr effect and self-assisted mechanism
Authors: Zeng Zhi 
Published: June 2024

Abstract
We present an efficient scheme for the complete hyperentangled Bell state analysis (HBSA) of photon system with polarization and two longitudinal momentum degrees of freedom (DOFs), resorting to weak cross-Kerr nonlinearity, linear optical elements and single photon detectors. In the process of distinguishing the 64 hyperentangled Bell states in three DOFs, the self-assisted mechanism is embedded, which makes our scheme simple and realizable. Moreover, we have discussed the applications of this complete HBSA scheme for high-capacity quantum communication protocols that are based on photonic hyperentanglement in three DOFs.
Landau quantization effects on damping Kawahara solitons in electron–positron–ion plasma in rotating ionized medium
Authors: El-Awady E I , Hussain S , Akhtar N 
Published: June 2024

Abstract
For the dynamics of three-dimensional electron–positron–ion plasmas, a fluid quantum hydrodynamic model is proposed by considering Landau quantization effects in dense plasma. Ion–neutral collisions in the presence of the Coriolis force are also considered. The application of the reductive perturbation technique produces a wave evolution equation represented by a damped Korteweg–de Vries equation. This equation, however, is insufficient for describing waves in our system at very low dispersion coefficients. As a result, we considered the highest-order perturbation, which resulted in the damped Kawahara equation. The effects of the magnetic field, Landau quantization, the ratio of positron density to electron density, the ratio of positron density to ion density, and the direction cosine on linear dispersion laws as well as soliton and conoidal solutions of the damped Kawahara equation are explored. The understanding from this research can contribute to the broader field of astrophysics and aid in the interpretation of observational data from white dwarfs.
Non-perturbative dynamics of flat-band systems with correlated disorder
Authors: Li 李 Qi 骐 , Liu 刘 Junfeng 军丰 , Liu 刘 Ke 克 , Hu 胡 Zi-Xiang 自翔 , Li 李 Zhou 舟 
Published: June 2024

Abstract
We develop a numerical method for the time evolution of Gaussian wave packets on flat-band lattices in the presence of correlated disorder. To achieve this, we introduce a method to generate random on-site energies with prescribed correlations. We verify this method with a one-dimensional (1D) cross-stitch model, and find good agreement with analytical results obtained from the disorder-dressed evolution equations. This allows us to reproduce previous findings, that disorder can mobilize 1D flat-band states which would otherwise remain localized. As explained by the corresponding disorder-dressed evolution equations, such mobilization requires an asymmetric disorder-induced coupling to dispersive bands, a condition that is generically not fulfilled when the flat-band is resonant with the dispersive bands at a Dirac point-like crossing. We exemplify this with the 1D Lieb lattice. While analytical expressions are not available for the two-dimensional (2D) system due to its complexity, we extend the numerical method to the 2D α–T
3 model, and find that the initial flat-band wave packet preserves its localization when α = 0, regardless of disorder and intersections. However, when α ≠ 0, the wave packet shifts in real space. We interpret this as a Berry phase controlled, disorder-induced wave-packet mobilization. In addition, we present density functional theory calculations of candidate materials, specifically Hg1–x
Cd
x
Te. The flat-band emerges near the Γ point (k = 0) in the Brillouin zone.
Phase structure evolution and its effect on magnetic and mechanical properties of B-doped Sm2Co17-type magnets with high Fe content
Authors: Li 李 Yao-Wen 耀文 , Liu 刘 Zhuang 壮 , Wu 吴 Hai-Chen 海辰 , Wang 王 Fang 芳 , Zhu 竺 Chao-Qun 超群 , Tan 谭 Dong-Liang 栋梁 , Liu 刘 Yu 宇 , Yang 羊 Yang 杨 , Zhang 张 Ming-Xiao 明晓 , Chen 陈 Ren-Jie 仁杰 , Yan 闫 A-Ru 阿儒 
Published: June 2024

Abstract
The unique cellular microstructure of Fe-rich Sm2Co17-type permanent magnets is closely associated with the structure of the solid solution precursor. We investigate the phase structure, magnetic properties, and mechanical behavior of B-doped Sm2Co17-type magnets with high Fe content. The doped B atoms can diffuse into the interstitial vacancy, resulting in lattice expansion and promote the homogenization of the phase organizational structure during the solid solution treatment in theory. However, the resulting second phase plays a dominant role to result in more microtwin structures and highly ordered 2 : 17R phases in the solid solution stage, which inhibits the ordering transformation of 1 : 7H phase during aging and affects the generation of the cellular structure, and to result in a decrease in magnetic properties, yet the interface formed between it and the matrix phase hinders the movement of dislocations and enhances the mechanical properties. Hence, the precipitation of high flexural strain grain boundary phase induced by B element doping is also a new and effective way to improve the flexural strain of Sm2Co17-type magnets. Our study provides a new understanding of the phase structure evolution and its effect on the magnetic and mechanical properties of Sm2Co17-type magnets with high Fe content.
Two-dimensional Cr2Cl3S3 Janus magnetic semiconductor with large magnetic exchange interaction and high-TC
Authors: Fu 伏 Lei 磊 , Li 李 Shasha 沙沙 , Bo 薄 Xiangyan 祥 , Ma 马 Sai 赛 , Li 李 Feng 峰 , Pu 普 Yong 勇 
Published: June 2024

Abstract
The two-dimensional (2D) Janus monolayers are promising in spintronic device application due to their enhanced magnetic couplings and Curie temperatures. Van der Waals CrCl3 monolayer has been experimentally proved to have an in-plane magnetic easy axis and a low Curie temperature of 17 K, which will limit its application in spintronic devices. In this work, we propose a new Janus monolayer Cr2Cl3S3 based on the first principles calculations. The phonon dispersion and elastic constants confirm that Janus monolayer Cr2Cl3S3 is dynamically and mechanically stable. Our Monte Carlo simulation results based on magnetic exchange constants reveal that Janus monolayer Cr2Cl3S3 is an intrinsic ferromagnetic semiconductor with T
C of 180 K, which is much higher than that of CrCl3 due to the enhanced ferromagnetic coupling caused by S substitution. Moreover, the magnetic easy axis of Janus Cr2Cl3S3 can be tuned to the perpendicular direction with a large magnetic anisotropy energy (MAE) of 142 μeV/Cr. Furthermore, the effect of biaxial strain on the magnetic property of Janus monolayer Cr2Cl3S3 is evaluated. It is found that the Curie temperature is more robust under tensile strain. This work indicates that the Janus monolayer Cr2Cl3S3 presents increased Curie temperature and out-of-plane magnetic easy axis, suggesting greater application potential in 2D spintronic devices.
An auto-segmented multi-time window dual-scale neural network for brain-computer interfaces based on event-related potentials
Authors: Zhao Xueqing , Xu Ren , Xu Ruitian , Wang Xingyu , Cichocki Andrzej , Jin Jing 
Published: June 2024

Abstract

Objective. Event-related potentials (ERPs) are cerebral responses to cognitive processes, also referred to as cognitive potentials. Accurately decoding ERPs can help to advance research on brain-computer interfaces (BCIs). The spatial pattern of ERP varies with time. In recent years, convolutional neural networks (CNNs) have shown promising results in electroencephalography (EEG) classification, specifically for ERP-based BCIs. Approach. This study proposes an auto-segmented multi-time window dual-scale neural network (AWDSNet). The combination of a multi-window design and a lightweight base network gives AWDSNet good performance at an acceptable cost of computing. For each individual, we create a time window set by calculating the correlation of signed R-squared values, which enables us to determine the length and number of windows automatically. The signal data are segmented based on the obtained window sets in sub-plus-global mode. Then, the multi-window data are fed into a dual-scale CNN model, where the sizes of the convolution kernels are determined by the window sizes. The use of dual-scale spatiotemporal convolution focuses on feature details while also having a large enough receptive length, and the grouping parallelism undermines the increase in the number of parameters that come with dual scaling. Main results. We evaluated the performance of AWDSNet on a public dataset and a self-collected dataset. A comparison was made with four popular methods including EEGNet, DeepConvNet, EEG-Inception, and PPNN. The experimental results show that AWDSNet has excellent classification performance with acceptable computational complexity. Significance. These results indicate that AWDSNet has great potential for applications in ERP decoding.
Multi-staged ERO2.0 simulation of material erosion and deposition in recessed mirror assemblies in JET and ITER
Authors: Rode S. , Brezinsek S. , Groth M. , Kirschner A. , Matveev D. , Moser L. , Pitts R.A. , Romazanov J. , Terra A. , Wauters T. , Wiesen S. 
Published: June 2024

Abstract
The deposition/erosion on optical diagnostic components—mirrors—is a critical issue in reactor class devices with long-pulsed high fluence plasma operation. The paper presents results of the three-dimensional Monte–Carlo code ERO2.0 for two diagnostic aperture and first mirror geometries to be deployed in ITER, along with a separate simulation study that aims to replicate results from an experimental first-mirror study carried out on JET. Promisingly, very little plasma and impurity deposition on mirrors for the anticipated plasma durations is found in the ERO2.0 modelling taking into account the current ITER Research Plan and a material mix with beryllium first wall and a tungsten divertor. The post-mortem analysis of mirrors exposed during the experiment and the initial benchmarking efforts on the JET mirror experiment are also broadly consistent, increasing the confidence in predictions for ITER.
Molecules with Spin and Vibronic Coupling Effects: A Computational Perspective
Authors: Sharma Ketan , Vasilyev Oleg A. , Miller Terry A. , Stanton John F. 
Published: June 2024

Abstract
While fundamental to molecular quantum mechanics, limitations of the Born-Oppenheimer Approximation (BOA) have long been known. Nonetheless, calculations that include molecular interactions, such as vibronic coupling and electron spin effects, that violate the BOA have remained a challenge due to their large demand on computational resources. The purpose of this paper is to describe two complementary software programs, SOCJT and XSIM, designed for efficient calculations that include these interactions. The programs are sufficiently general and user friendly that they can be readily applied to a variety of molecules of different symmetries, state degeneracies, and interaction strengths. The programs can typically produce spin-vibronic eigenvalues and eigenvectors with sufficient accuracy for the analysis and interpretation of molecular spectra with features attributable to violations of the BOA. The two programs utilize different matrix representations of the molecular Hamiltonian, with XSIM being Cartesian based and SOCJT being cylindrically based, and their advantages/disadvantages are discussed. Several algorithms can be chosen to obtain the Hamiltonian’s eigenvalues and eigenvectors and their speed and memory usage are compared. Examples of application of SOCJT and XSIM to explain spectral observations for particular molecules are briefly reviewed.
How the Amount of Hartree-Fock Exchange Affects the Observation of the Pseudo Jahn-Teller Effect
Authors: Maley S M , Mawhinney R C 
Published: June 2024

Abstract
Heavy group 14 analogs of planar carbon molecules are well known to prefer bent or pyramidalized geometries. The pseudo Jahn-Teller effect (pJTE) is a general approach to understanding the origin of such molecular geometries. Computationally intensive multi-reference post Hartree-Fock methods are generally required to obtain values relevant to the pJTE. However, an alternative approach, using more computationally efficient density functional theory (DFT) and fitting a model vibronic Hamiltonian, can account for the pJTE parameters. Previous studies have detailed the effect of both integration grid size and exact exchange on various properties including the nature of stationary points (i.e., transition structure v. minimum) on potential energy surfaces but none have addressed the root cause of such discrepancies. In this work we examine two contentious stationary points belonging to planar disilene and 2Si TCNQ from the perspective of the pseudo Jahn-Teller effect (pJTE) using DFT methods. First the planar stationary points are characterized using a variety of model chemistries and integration grids. The effect of the amount of Hartree-Fock exchange is then studied and the usage of DFT for assessing pJT parameters is explored. It is shown that the DFT approach is a viable alternative for determining values relevant to the pJTE. A complementary cusp catastrophe theory approach to the problem is also introduced. Difficulties associated with the DFT-based approach to the study of the pJTE are discussed and changes in the electronic structure are explored using the Quantum Theory of Atoms in Molecules.
Multi-state vibronic dynamics of the benzene cation: Combined multi-mode Jahn-Teller and Pseudo Jahn-Teller Effects
Authors: Hannibal Valentin D. , Menger Maximilian F.S.J. , Köppel Horst 
Published: June 2024

Abstract
The multi-state vibronic interactions in the benzene radical cation are investigated theoretically, based on an ab initio quantum dynamical approach. The three lowest doubly degenerate and two lowest non-degenerate electronic states are included, amounting to eight electronic component states and 28 vibrational degrees of freedom. The multi-mode dynamical Jahn-Teller as well as pseudo Jahn-Teller effects are included on an equal footing. This becomes possible by employing the Multiconfigurational Time-Dependent Hartree Method and its multi-layer extension for the wavepacket propagation underlying the dynamical treatment. The results indicate a step wise population transfer from higher to lower-energy electronic states. The transfer between the highest (

E

∼

and

D

∼

states) is extremely fast which is made plausible by their energetic proximity. On the other hand the transfer is not complete and does not comprise the

X

∼

ground state. Rather, a substantial part of the population gets trapped in the lowest excited (

B

∼

) state. The phenomenon is briefly discussed and calls for future work on this intricate dynamical system.
Pseudo-Jahn-Teller effect in deprotonated dimethyl amino phenyl substituted phthalocyanine
Authors: Breza Martin 
Published: June 2024

Abstract
Geometries of dimethyl amino phenyl substituted phtalocyanine deprotonated at two nitrogen atoms [dmaphPc]q, q = -2, -1 and 0, were optimized within the D4h symmetry group and its subgroups. Their excited states were evaluated using the TD-DFT treatment. Using an epikernel principle method based on the symmetries of the imaginary vibrations of the optimized geometries and the symmetries of the corresponding excited states, the symmetry descent paths D4h → D4 for [dmaphPc]2-, D4h → D2 for [dmaphPc]−, and D4h → C2 for [dmaphPc]0 were explained as a consequence of the pseudo-Jahn-Teller effect.
Jahn-Teller induced microwave spectra of the C70
+ fullerene cation.
Authors: Nemes Laszlo 
Published: June 2024

Abstract
The C70 molecule is apolar. Upon ionization Jahn-Teller effects occur that distort the D5h neutral symmetry to Cs. This point group is polar thus ionization induces a permanent electric dipole moment in C70. The goal of the present calculations is to compute the equilibrium geometry and dipole moment of the C70
+ cation by various DFT methods and to simulate microwave spectra. Using the Gaussian16 quantum chemistry program rotational constants, Cartesian dipole moment components, and the resultant dipole, as well as the Jahn-Teller stabilization energy and the HOMO-LUMO gaps were obtained. The microwave rotational spectra at gas phase temperatures 2.73 K and 10K were simulated using the Pgopher software. These spectra may serve as starting point for laboratory microwave measurements and as screening guide in radio astronomical searches. The static Jahn-Teller effect in C70
+ is the consequence of the mixing of the two highest ground state occupied orbitals, thus it is a pseudo Jahn-Teller effect.
Ultrasonic investigation of the Jahn-Teller effect in BaF2:Cu crystal
Authors: Ofitserova N Yu , Sarychev M N , Zhevstovskikh I V , Ulanov V A , Surikov V T , Averkiev N S , Gudkov V V 
Published: June 2024

Abstract
The present work is an ultrasonic study of the temperature dependence of the dynamic elastic moduli in the single crystal of BaF2 doped with Cu. Similar to the observation in CaF2:Cu2+, the temperature dependence of the real and imaginary parts of the elastic modulus c
44 manifest typical anomalies, which are induced by the Jahn-Teller effect in the T ⊗ (e + t
2) case with orthorhombic or trigonal stable structures. However, in BaF2:Cu, these anomalies are much smaller than in CaF2:Cu2+. We attribute this difference to the lower concentration of the Cu2+ dopants that isovalently replace Ba2+ in the BaF2 matrix. Our study of BaF2:Cu reveals the following relaxation mechanisms: thermal activation, tunneling through the potential energy barrier, and two-phonon relaxation.
Vibronic order and magnetism in cubic 5d
1 double perovskite compounds
Authors: Iwahara Naoya , Huang Zhishuo , Chibotaru Liviu F. 
Published: June 2024

Abstract
Cubic 5d
1 transition metal double perovskites exhibit various multipolar phases, which have not been unvailed within the spin-orbit based theories. A missing piece in the previous theories is the vibronic coupling on each site. In each 5d
1 transition metal sites, four-fold degenerate ground spin-orbit coupled states interact with Jahn-Teller active vibration, which gives rise to the development of the dynamic Jahn-Teller effect. Here, we incorporate the spin-orbit coupling and dynamic Jahn-Teller effect and describe all the ordered states reported for the 5d
1 double perovskites. We defined vibronic quadrupole moment and developed a spin-vibronic quadrupole model from the microscopic interactions in the double perovskites. The spin-vibronic model shows a rich mean-field phase diagram including the ordered phases that never appear in the conventional spin-orbit theories. Various ordered phases develop because the ordering of the vibronic states (vibronic order) gives strong impact on the magnetic orderings. The zero and finite temperature spin-vibronic ordered phases explain the puzzling orderings found in Cs2TaCl6 and Ba2MgReO6.
The Jahn-Teller Effect on One-dimensional Copper-Oxalate Framework Cu(μ-C2O4)[(CH3)2NCH2CH2N(CH3)2]·4H2O
Authors: Zhang Bin , Zhang Yan , Wang Zheming , Wang Dongwei , Sun Yang , Liang Tongling , Zhao Zhijuan , Zhang Xiaoyu , Qu Baolong , Feng Rongjuan , Li Qiaolian , Luo Xiaofei , Liu Mei , Zhang Xueying , Zhu Daoben 
Published: June 2024

Abstract
A one-dimensional copper-oxalate framework is obtained. The Jahn-Teller distorted Cu(II) is octahedrally coordinated by four O from two bisbidentate oxalates and two N from one bidentate N, N, N’ N’-tetramethyldiamine and forms a one-dimensional zigzag chain. There are hydrogen bonds between H2O and oxalate and between H2O. In one of H2O, the geometry of two O–H and two O…H–O bonds is same as tetrahedron of H2O in ice. Ferromagnetic interaction is observed. No long-range ordering is observed above 2 K
Heterogeneity in vegetation recovery rates post-flash droughts across different ecosystems
Authors: Lu Mengge , Sun Huaiwei , Cheng Lei , Li Siyue , Qin Hui , Yi Shanzhen , Zhang Hong , Zhang Wenxin 
Published: June 2024

Abstract
Flash droughts, as sub-seasonal phenomena, are characterized by their rapid onset and significant impact on terrestrial ecosystems. However, understanding how vegetation responds to flash droughts and the mechanisms governing vegetation recovery remains elusive. Here, we analysed the response of vegetation productivity to flash droughts and identified the most relevant drivers controlling vegetation recovery using two soil moisture datasets (ERA5-land and Global Land Data Assimilation System) and two satellite-based vegetation productivity proxies (gross primary productivity, and solar-induced chlorophyll fluorescence). Our results show that South China and Northeast China stand out as hotspots for flash droughts, with higher frequency and speed. Notably, although the frequency of flash droughts in cropland is relatively low, and their speed is very high, with a median of 10.9% per pentad. Most ecosystems can recover to their normal state within 25 d. Vegetation with shallow roots, such as cropland and grassland, responds rapidly to flash droughts. Ecosystems generally exhibit extended response time with increasing plant rooting depth. The recovery rate of vegetation productivity from flash droughts is mainly controlled by vegetation physiology (decline rate of productivity upon exposure to flash drought) and modulated by flash drought characteristics, especially severity for forests and speed for cropland and grassland. This study provides valuable insights into the mechanisms underlying vegetation responses to flash droughts.