Calculation Of Magnetic Moment Research Articles

Molecular pentaquark magnetic moments in heavy pentaquark chiral perturbation theory

We propose a new heavy pentaquark chiral perturbation theory for the recently observed hidden-charm pentaquark states by LHCb Collaboration. With the pentaquark chiral Lagrangians, we present a parameter-free calculation of the octet molecular pentaquark magnetic moments up to one-loop level. We improve the quark model description of the data when we include the leading SU(3) breaking effects coming from the one-loop corrections. Without any experimental inputs, our predictions are so simple and unique that we regard them as a theoretical benchmark to be compared with experiments as well as other theoretical models. Published by the American Physical Society 2024

Theoretical study of a Ti4 cluster interacting with B-doped and non-doped multivacancy graphene

A density functional theory study was performed to understand the interactions of a small Ti4 cluster with multi-vacancy graphene. We also consider the effect produced by the B-doping of the vacancy defect. In this sense, we analyze the binding mechanisms of the metal cluster. The focus is set on its stability on the substrate, geometrical structure and the interactions participating between the cluster and graphene substrate. A qualitative study of the principal bonds was carried out employing overlap population and bond order chemical descriptors. Additionally, as an attempt to comprehend better the electronic structure and related properties, we performed total density of states, band structure and magnetic moment calculations to characterize the electrical and magnetic properties of the B-doped and non-doped systems.

Calculation of lepton magnetic moments in quantum electrodynamics: A justification of the flexible divergence elimination method

The flexible method of reduction to finite integrals, briefly described in earlier publications of the author, is described in detail. The method is suitable for the calculation of all quantum electrodynamical contributions to the magnetic moments of leptons. It includes mass-dependent contributions. The method removes all divergences (UV, IR, and mixed) point-by-point in Feynman parametric space without any usage of limitlike regularizations. It yields a finite integral for each individual Feynman graph. The subtraction procedure is based on the use of linear operators applied to the Feynman amplitudes of UV-divergent subgraphs; a placement of all terms in the same Feynman parametric space is implied. The final result is simply the sum of the individual graph contributions; no residual renormalization is required. The method also allows us to split the total contribution into the contributions of small gauge-invariant classes. The procedure offers a great freedom in the choice of the linear operators. This freedom can be used for improving the computation speed and for a reliability check. The mechanism of divergence elimination is explained, as well as the equivalence of the method and the on shell renormalization. For illustrative purposes, all 4-loop contributions to the anomalous magnetic moments of the electron and muon are given for each small gauge-invariant class, as well as their comparison with previously known results. This also includes the contributions that depend on the ratios of the tau-lepton mass to the electron and muon mass. Published by the American Physical Society 2024

Inversion of Target Magnetic Moments Based on Scalar Magnetic Anomaly Signals

As a key physical property of underwater ferromagnetic targets, magnetic moment can reflect important information such as the mass and heading of the target. However, most of the current magnetic moment estimation methods rely on vector magnetic field sensors or sensor arrays to measure the magnetic field, which limits its application in remote target magnetic moment calculation on mobile platforms to some extent. To solve this problem, a real-time magnetic moment inversion method based on the high-precision scalar magnetic measurement data of a high-speed moving platform is proposed in this paper. The method allows the estimation of the magnetic moment of underwater ferromagnetic targets by the scalar magnetic measurement data of an optical pump magnetic field sensor mounted on a high-speed moving platform. The experimental results show that this method has high precision in estimating magnetic moment; the average error of the magnetic moment amplitude was only 5.85%, while the average errors of the magnetic moment inclination and magnetic moment deflection were 1.58° and 2.79°, respectively. These results provide a new and effective way to estimate the magnetic moment of underwater ferromagnetic targets and are expected to have important practical applications.

Ab-initio study on structural, magnetic, electronic and optical properties of SrCo1−xAxO3 (A = Fe or Cr, x = 0.125 and 0.25)

Herein, a first-principles study on the structural, electronic, optical and magnetic properties of SrCo[Formula: see text]AxO3 ([Formula: see text] or Cr, [Formula: see text] and 0.25) was conducted. For all calculations, ultrasoft pseudo-potentials plane wave (USPPW) and the generalized gradient approximation (GGA) with the default exchange-correlation parameterization of Perdew–Burke–Ernzerhof (PBE) were employed and with Hubbard correction. The crystal structures of SrCo[Formula: see text]A[Formula: see text]O3 and SrCo[Formula: see text]A[Formula: see text]O3 ([Formula: see text] or Cr) are determined as a supercell of [Formula: see text] cell cubic perovskite structure (Pm-3m) with symmetry space group No. 221. No energy gap was observed at the Fermi level for both SrCo[Formula: see text]Cr[Formula: see text]O3 and SrCo[Formula: see text]Cr[Formula: see text]O3 compounds, indicating their metallic properties. The magnetic moment calculations showed that the doping of Fe into SrCoO3 resulted in a higher net magnetic moment and all materials studied here was ferromagnetic ground states. Dielectric functions indicate the metallic conductivity for all materials studied here. The different values of the real part for materials present that this material has a Drude-like dielectric function behavior.

Auxiliary field diffusion Monte Carlo calculations of magnetic moments of light nuclei with chiral effective field theory interactions

Auxiliary field diffusion Monte Carlo calculations of magnetic moments of light nuclei with chiral effective field theory interactions

Strong ultrafast demagnetization due to the intraband transitions

Demagnetization in ferromagnetic transition metals driven by a femtosecond laser pulse is a fundamental problem in solid state physics, and its understanding is essential to the development of spintronic devices. Ab initio calculation of time-dependent magnetic moment in the velocity gauge so far has not been successful in reproducing the large amount of demagnetization observed in experiments. In this work, we propose a method to incorporate intraband transitions within the velocity gauge through a convective derivative in the crystal momentum space. Our results for transition-element bulk crystals (bcc Fe, hcp Co and fcc Ni) based on the time-dependent quantum Liouville equation show a dramatic enhancement in the amount of demagnetization after the inclusion of an intraband term, in agreement with experiments. We also find that the effect of intraband transitions on each ferromagnetic material is distinctly different because of their band structure and spin property differences. Our finding has a far-reaching impact on understanding of ultrafast demagnetization.

Study of Magnetic, Optical, Electronic and Thermodynamic Effects in Thallium Rare Earth Disulphides (TlRES2, RE= Tb- Er)

In the present research work, we have investigated density of electronic states, electronic band structure, magnetic structure, optical spectra and temperature dependent thermodynamic characteristics of thallium rare earth sulphides, TlRES2 (RE: Tb-Er) using FP-LAPW method and PBE-GGA exchange correlation within DFT. The electronic structure pointed out that TlRES2 compounds show half metallic character. The magnetic moment and spin polarization calculations prove that TlRES2 are fully spin polarized compounds with ferromagnetic nature. Optical spectra show that intraband transitions occur in infrared (IR) regime due to half metallic character of TlRES2 and behave as opaque in ultraviolet (UV) region. High refractive index in IR regime also show metallic character and high peak in UV regime show slow propagation of light in UV regime. The reflection coefficient is found maximum (~50–60%) in UV regime. Greater energy loss has been seen on the higher energy side, which corresponds to the stimulation of plasmons by electrons moving through the compounds. Plasma resonances lead to the frequent peaks at ~ 6.0 eV, 11.0 eV, and 12.0 eV. According to calculations made using the quasi-harmonic Debye model, TlRES2 compounds are dimensionally less stable (i.e., much hard), have poor thermal conductivity, and experience faster-than-average disorder with increasing the temperature.

Investigating the Structural, Electronic, and Topological Properties of [BMIm][Fe(NO)2Cl2] Magnetic Ionic Liquid: Density Functional Theory Approaches

Magnetic ionic liquids (MILs) show clear superiority over conventional ionic liquids suitably nested in many applications, particularly in medicine and drug delivery engineering. The easy way of collecting them using an external magnet and separating them from the reaction mixture is a favorable and unique technique. A magnetic imidazolium-based IL, including iron coordinated with -NO and chloride ligands ([BMIm][Fe(NO)2Cl2]) (BMIm = 1-n-butyl-3-methyl-imidazolium), has been studied using density functional theory. Such dinitrosyl iron compounds are significant as NO-saving sources and carriers because of their longer physiological lifetime compared with molecular NO. The dependability of the calculations was examined and elucidated at three different methods (M06-2X, B3LYP, and B3LYP-D3) to unravel the importance of noncovalent interactions, including dispersion and H-bonding. Also, the effect of a large basis set on different features of this MIL was assessed. This research is a pioneer in theoretically characterizing the type of -NO moiety of this open-shell dinitrosyl iron compound. The complicated structure of the dinitrosyliron unit was determined by the geometrical parameters, stretching frequencies, and magnetic moment calculation. Based on these fingerprint data, the predominant form of two NO's in this MIL is the nitroxyl anion NO-, rather than ṄO or NO+. Unraveling that one of the NO ligands structurally is dangling enhances the application of this MIL as a NO-saving and source compound. Consequently, Fe3+ is identified as the major oxidation state of the iron atom, leading to the MIL with a strong magnetic moment (of 5.22μB).

A Flexible Divergence Elimination Method for Calculating Lepton Magnetic Moments in Quantum Electrodynamics

A precise calculation of the lepton anomalous magnetic moments (AMM) requires an evaluation of the quantum electrodynamics (QED) Feynman diagrams up to five independent loops. The complicated structure of ultraviolet (UV), infrared (IR) and mixed divergences in the corresponding integrals makes it difficult to calculate these high-order contributions in reasonable computer time frame.We demonstrate a method that eliminates all divergences point by point in Feynman parametric space (before integration) and possesses a flexibility that can be used for improving the precision of the numerical integration. This flexibility is especially actual for calculating the contributions of the Feynman diagrams with electron loops to the muon AMM. 3-loop and 4-loop numerical test results are provided.The subtraction procedure is based on a forest formula with linear operators applied to the Feynman amplitudes of UV divergent subdiagrams. It is similar to BPHZ; the difference is in the linear operators used and in the way of combining them. It is equivalent to the on-shell renormalization after summation over diagrams: no residual renormalization is required.

A computational insight into the intrinsic, Si-decorated and vacancy-defected γ-graphyne nanoribbon towards adsorption of CO2 and O2 molecules

In this study, the effects of decorating a silicon (Si) atom and applying a single vacancy defect on an armchair γ-graphyne nanoribbon (A-γ-GyNR) are investigated toward CO2 and O2 molecules adsorption. The magnetic and electronic transport properties, including the calculation of adsorption energy, charge transfer, magnetic moment, band structure, phonon dispersion and density of state (DOS), have been studied using the spin-polarized density functional theory (DFT) method. The stability of the proposed substrates is measured and different positions for gas molecules are considered. The results reveal that the highest amounts of adsorption energy of CO2 (0.63 eV) and O2 (2.2 eV) molecules belong to the substrate decorated with the Si atom in the 12-membered ring (H1) and acetylene linkage (B3), respectively. In addition, the removal of a carbon atom with sp hybridization improves the O2 molecule adsorption by 3.34 times compared to the primary substrate (P-GyNR). According to the recovery time calculations, the most appropriate desorption time is related to T1-M1 model. The current–voltage characteristic confirms that the resistance of the introduced sensors fully changed after sensing. This work can be considered as an effective step toward understanding and developing A-γ-GyNR-based gas sensors.

Calculation of magnetic moments of Λ-hypernuclei c , o and ca

The magnetic moments of Λ-hypernuclei are the most interesting observables which provide a highly sensitive probe of lambda in the hypernuclei structure and also supply direct information on hyperon-nucleon interactions. In this work, we derive the magnetic moments of Λ-hypernuclei such as O , C and Ca employing a relativistic approach in the presence of the Dirac equation and the spin-orbital potential in their ground and excited states, i.e. the 1S1/2, 1P3/2 and 1P1/2 states. We, then, extract an analytic solution for the wave function of hyperon which is needed for computing the magnetic moments of Λ-hypernuclei. The hypernuclei magnetic moments are the magnetic moment of the last unpaired baryon for the odd mass hypernuclei, therefore, in our work we study the hypernuclear magnetic moment with one Lambda added to a closed-shell core of nucleons. Since Λ-hypernuclei is an isoscalar particle it is possible to directly probe the modified core current electromagnetically.

Diatomic-py: A Python module for calculating the rotational and hyperfine structure of 1Σ molecules

We present a computer program to calculate the quantised rotational and hyperfine energy levels of Σ1 diatomic molecules in the presence of dc electric, dc magnetic, and off-resonant optical fields. Our program is applicable to the bialkali molecules used in ongoing state-of-the-art experiments with ultracold molecular gases. We include functions for the calculation of space-fixed electric dipole moments, magnetic moments and transition dipole moments. Program summaryProgram Title: Diatomic-PyCPC Library link to program files:https://doi.org/10.17632/3yfxnh5bn5.1Developer's repository link:https://doi.org/10.5281/zenodo.6632148Licensing provisions: BSD 3-clauseProgramming language: Python ≥ 3.7Nature of problem: Calculation of the rotational and hyperfine structure of Σ1 molecules in the presence of dc magnetic, dc electric, and off-resonant laser fields.Solution method: A matrix representation of the Hamiltonian is constructed in the uncoupled basis set. Eigenstates and eigenenergies are calculated by numerical diagonalization of the Hamiltonian.Additional comments including restrictions and unusual features: Restricted to calculating the Stark and Zeeman shifts with co-axial electric and magnetic fields.

Isolation and Characterization of a Highly Reducing Aqueous Chromium(II) Complex

The highly reducing CrII-(1,3-propylenediaminetetraacetate) (CrPDTA) complex (-1.1 V vs SHE) has been isolated from aqueous solution and the solid-state structure is described. The reduced CrIIPDTA complex is characterized by single-crystal X-ray diffraction, elemental analysis, infrared spectroscopy, UV-vis spectroscopy, magnetic moment, and density functional theory calculations. The concentration profile, state of charge, and pH of CrPDTA electrolyte were monitored in a flow battery system in situ by absorption spectroscopy and a pH probe. The stability of CrIIPDTA in aqueous environments is demonstrated by the ability to isolate CaCrPDTA, despite the common misconception that water spontaneously evolves hydrogen at such potentials. The reduced CrIIPDTA prevents water from coordinating to the metal center by maintaining the same coordinatively saturated pseudo-octahedral structure as the oxidized CrIIIPDTA, despite experiencing an increased geometric strain from a Jahn-Teller distortion of the high-spin CrII ion. The important difference between solvent reactivity and solvent thermodynamic window is examined by comparing the electrochemical behavior of the reduced species of CrPDTA in various organic solvents to its behavior in aqueous solution. When examined in tetrahydrofuran (THF), the reduction potential of CrPDTA is observed to be -1.19 V vs cobaltocene (-2.52 V vs ferrocene). Reduced CrPDTA in aqueous solution is also exposed to atmospheric O2 without exhibiting any decomposition of the Cr(III) or Cr(II) species. The techniques detailed provide a higher standard method of characterization for flow battery electrolyte species.

Optical Activity of Spin-Forbidden Electronic Transitions in Metal Complexes from Time-Dependent Density Functional Theory with Spin-Orbit Coupling.

The calculation of magnetic transition dipole moments and rotatory strengths was implemented at the zeroth‐order regular approximation (ZORA) two‐component relativistic time‐dependent density functional theory (TDDFT) level. The circular dichroism of the spin‐forbidden ligand‐field transitions of tris(ethylenediamine)cobalt(III) computed in this way agrees very well with available measurements. Phosphorescence dissymmetry factors glum and the corresponding lifetimes are evaluated for three N‐heterocyclic‐carbene‐based iridium complexes, two of which contain helicene moieties, and for two platinahelicenes. The agreement with experimental data is satisfactory. The calculations reproduce the signs and order of magnitude of glum , and the large variations of phosphorescence lifetimes among the systems. The electron spin contribution to the magnetic transition dipole moment is shown to be important in all of the computations.

Определение дипольного магнитного момента по измерениям на незамкнутой поверхности

Object and purpose of research. This paper discusses a quadrature-based method of dipole magnetic moment (DMM) calculation as per magnetic field measurement data for the open surface encompassing magnetic field sources. The purpose of the study was to modify this method for the case when measurement data are not available for certain areas on the surface (in other words, when the surface is not closed). Materials and methods. The paper describes magnetic dipole calculation methods, as well as the publications discuss-ing their efficiency. The method suggested in this paper basically substitutes the lacking magnetic field data by the values for pre-defined type of source, thus giving the correction coefficients needed to take into account the contribution of lacking areas. Main results. The paper suggests the methods for taking into account the missing parts of the open measurement surface in quadrature-based DMM calculation procedure. Calculation errors of DMM components for magnetic fields of various structure are estimated as per the solution for a series of test problems. Conclusion. The quadrature method offered in this study offers more accurate DMM calculation. The expressions given in the paper could be used to calculate DMM components as per magnetic field measurements for the generatrices of cylindrical surface, and the approach suggested in this study could be applied to arbitrary open surfaces.

Effect of Mn doping and point vacancy on stability and magnetism of ZnO

Understanding the source of magnetism in Mn doped ZnO (ZnO:Mn) is an active area of research, made difficult experimentally by the challenge of controlling point vacancies in ZnO:Mn. Therefore, the stability and magnetic properties of ZnO:Mn with point vacancies were studied by first-principles calculations based on density functional theory (DFT). Formation energy and magnetic moment calculation results show that Mn prefers to cluster in ZnO:Mn. This clustering can become uniformly distributed through modifications by Zn vacancies (V Zn ) or O vacancies (Vo). Magnetic analysis shows that Mn dopant in Zn site (ZnO:Mn Zn ) coupled with V Zn or interstitial Mn (Mn i ) coupled with V O makes ZnO having long-range ordered ferromagnetism (FM) and an increased Curie temperature ( Tc ) above room-temperature. The ZnO:Mn Zn with V Zn exhibits obvious half-metallic characteristics that are of essential benefit to the design and preparation of a new-type of spin-electron injection source dilute magnetic semiconductor. The magnetic sources of ZnO:Mn Zn with V Zn and Mn i -doped ZnO (ZnO:Mn i ) with V O arise from carrier-mediated magnetic interaction and the double exchange of Mn3d, O2p and Zn4s orbitals, consistent with the theories of average field approximation and the double exchange mechanism.

Phase driven magnetic and optoelectronic properties of La2CrNiO6: A DFT and Monte Carlo perspective

In search of the ferromagnetic insulators for spintronic device applications, we have studied the electronic, optical and magnetic properties of La2CrNiO6 (LCNO) using the first principle density functional theory (DFT) and the Monte Carlo simulation technique. Firstly, we have adopted the sol-gel method for the preparation of LCNO and refined the X-ray diffracted value using the Fullprof suite under the Rietveld mechanism. The obtained orthorhombic Pbnm and cubic Fm-3m space groups are used as the input of the DFT calculations. Both the structures have shown the half metallicity and insulting bandgap towards the majority and minority spin direction, respectively. From the magnetic moment calculations, we have seen the low spin state of Ni3+, and the double exchange (DE) interaction are responsible for the ferromagnetic structure of LCNO. The optical dielectric constant is ten, and the refractive index is 3.2 for orthorhombic structure. The transition temperature (TC) is determined to be 110 ​K from the MCS study, which has well agreed with experimental value (111 ​K). The RCP value is determined to 12 ​J/kg with a 5 ​T applied field, which is good for magnetocaloric applications.

Interplay between breathing-mode distortions and magnetic order in rare-earth nickelates from ab initio magnetic models

We use density-functional theory calculations to explore the magnetic properties of perovskite rare-earth nickelates, $\mathcal{R}$NiO$_3$, by constructing microscopic magnetic models containing all relevant exchange interactions via Wannierization and Green's function techniques. These models elucidate the mechanism behind the formation of antiferromagnetic order with the experimentally observed propagation vector, and explain the reason previous DFT plus Hubbard $U$ calculations favored ferromagnetic order. We perform calculations of magnetic moments and exchange-coupling parameters for different amplitudes of the $R_1^+$ breathing mode distortion, which results in expanded and compressed NiO$_6$ octahedra. We find that the magnetic moment vanishes for the "short bond" nickels, i.e., the ones in the compressed octahedra. The inclusion of spin-orbit coupling demonstrates that the magnetic anisotropy is very small, while the magnetic moment of the short bond nickel atoms tend to zero even for the noncollinear case. Our results provide a clear picture of the trends of the magnetic order across the nickelate series and give insights into the coupling between magnetic order and structural distortions.

Magnetic Moment Measurement Method Based on Magnetic Sensor Array

The magnetic moment measurement method based on magnetic sensor array is proposed to solve the problems of cumbersome calculation process and low inversion accuracy in the current magnetic moment calculation methods. Based on the concepts of magnetic field intensity, magnetic gradient tensor and Frobenius norm, this method can use the magnetic field information collected by magnetic sensor array to calculate the magnetic moment vector. The factors that may affect the measurement effect, such as sensor array structure, sensor precision and baseline size, are analyzed by simulation, and the advantages and disadvantages of three magnetic moment measurement methods based on magnetic sensor array are compared. Simulation results show that the proposed method is flexible in use, convenient in measurement, accurate in results, and has strong feasibility and reliability in geological survey and other applications.