Pub Date : 2024-03-18DOI: 10.1088/1361-6455/ad2e2f
Nilakantha Meher
We provide a MATLAB numerical guide at the beginner level to support students starting their research careers in theoretical quantum optics and related areas. These resources are also valuable for undergraduate and graduate students working on semester projects in similar fields.
{"title":"Quantum optics in MATLAB","authors":"Nilakantha Meher","doi":"10.1088/1361-6455/ad2e2f","DOIUrl":"https://doi.org/10.1088/1361-6455/ad2e2f","url":null,"abstract":"We provide a MATLAB numerical guide at the beginner level to support students starting their research careers in theoretical quantum optics and related areas. These resources are also valuable for undergraduate and graduate students working on semester projects in similar fields.","PeriodicalId":16826,"journal":{"name":"Journal of Physics B: Atomic, Molecular and Optical Physics","volume":"38 1","pages":""},"PeriodicalIF":1.6,"publicationDate":"2024-03-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140316180","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}
Pub Date : 2024-03-18DOI: 10.1088/1361-6455/ad2e2a
A Niggas, M Werl, F Aumayr, R A Wilhelm
Electron beam ion traps allow studies of slow highly charged ion transmission through freestanding 2D materials as an universal testbed for surface science under extreme conditions. Here we review recent studies on charge exchange of highly charged ions in 2D materials. Since the interaction time with these atomically thin materials is limited to only a few femtoseconds, an indirect timing information will be gained. We will therefore discuss the interaction separated in three participating time regimes: energy deposition (charge exchange), energy release (secondary particle emission), and energy retention (material modification).
{"title":"Charge exchange of slow highly charged ions from an electron beam ion trap with surfaces and 2D materials","authors":"A Niggas, M Werl, F Aumayr, R A Wilhelm","doi":"10.1088/1361-6455/ad2e2a","DOIUrl":"https://doi.org/10.1088/1361-6455/ad2e2a","url":null,"abstract":"Electron beam ion traps allow studies of slow highly charged ion transmission through freestanding 2D materials as an universal testbed for surface science under extreme conditions. Here we review recent studies on charge exchange of highly charged ions in 2D materials. Since the interaction time with these atomically thin materials is limited to only a few femtoseconds, an indirect timing information will be gained. We will therefore discuss the interaction separated in three participating time regimes: energy deposition (charge exchange), energy release (secondary particle emission), and energy retention (material modification).","PeriodicalId":16826,"journal":{"name":"Journal of Physics B: Atomic, Molecular and Optical Physics","volume":"34 1","pages":""},"PeriodicalIF":1.6,"publicationDate":"2024-03-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140316162","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}
Pub Date : 2024-03-14DOI: 10.1088/1361-6455/ad2e31
Mercè Deumal, Jordi Ribas-Ariño, Michael A Robb
We have simulated two mechanisms, direct and superexchange, for the electron transfer in a model Bis(hydrazine) Radical Cation, which consists of two hydrazine moieties coupled by a benzene ring. The computations, that are inspired by the attochemistry approach, focus on the electron dynamics arising from a coherent superposition of four cationic states. The electron dynamics, originating from a solution of the time dependent Schrödinger equation within the Ehrenfest method, is coupled to the relaxation of the nuclei. Both direct (ca. 15 fs dynamics) and superexchange (ca. 2 fs dynamics) mechanisms are observed and turn out to lie on a continuum depending on the strength of the coupling of the benzene bridge electron dynamics with the hydrazine chromophore dynamics. This contrasts with the chemical pathway approach where the direct mechanism is completely non-adiabatic via a conical intersection, while the superexchange mechanism involves an intermediate radical with the unpaired electron localized on the benzene ring. Thus, with the attochemistry-inspired electron dynamics approach, one can distinguish direct from superexchange mechanisms depending on the strength of the coupling of two types of electron dynamics: the slow hydrazine dynamics (ca. 15 fs) and the fast benzene linker dynamics (ca. 2 fs). In this model bis(hydrazine) radical cation, only when the intermediate coupler is in an anti-quinoid state, does one see the coupling of the bridge and hydrazine chromophore dynamics.
{"title":"Using ‘designer’ coherences to control electron transfer in a model bis(hydrazine) radical cation: can we still distinguish between direct and superexchange mechanisms?","authors":"Mercè Deumal, Jordi Ribas-Ariño, Michael A Robb","doi":"10.1088/1361-6455/ad2e31","DOIUrl":"https://doi.org/10.1088/1361-6455/ad2e31","url":null,"abstract":"We have simulated two mechanisms, direct and superexchange, for the electron transfer in a <italic toggle=\"yes\">model Bis(hydrazine) Radical Cation</italic>, which consists of two hydrazine moieties coupled by a benzene ring. The computations, that are inspired by the attochemistry approach, focus on the electron dynamics arising from a coherent superposition of four cationic states. The electron dynamics, originating from a solution of the time dependent Schrödinger equation within the Ehrenfest method, is coupled to the relaxation of the nuclei. Both direct (<italic toggle=\"yes\">ca</italic>. 15 fs dynamics) and superexchange (<italic toggle=\"yes\">ca.</italic> 2 fs dynamics) mechanisms are observed and turn out to lie on a continuum depending on the strength of the coupling of the benzene bridge electron dynamics with the hydrazine chromophore dynamics. This contrasts with the chemical pathway approach where the direct mechanism is completely non-adiabatic via a conical intersection, while the superexchange mechanism involves an intermediate radical with the unpaired electron localized on the benzene ring. Thus, with the attochemistry-inspired electron dynamics approach, one can distinguish direct from superexchange mechanisms depending on the strength of the coupling of two types of electron dynamics: the slow hydrazine dynamics (<italic toggle=\"yes\">ca</italic>. 15 fs) and the fast benzene linker dynamics (<italic toggle=\"yes\">ca.</italic> 2 fs). In this model bis(hydrazine) radical cation, only when the intermediate coupler is in an anti-quinoid state, does one see the coupling of the bridge and hydrazine chromophore dynamics.","PeriodicalId":16826,"journal":{"name":"Journal of Physics B: Atomic, Molecular and Optical Physics","volume":"37 1","pages":""},"PeriodicalIF":1.6,"publicationDate":"2024-03-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140316089","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}
Nanoparticles devoted to improve radiotherapy treatments are an efficient tool if they can induce the formation of deleterious species in the tumor. Their interaction with radiation is responsible for radical production but in spite of the numerous studies mostly with cells, no consensus has been reached about radical formation mechanism. In order to gain knowledge in the physico-chemical step of this phenomenon, we applied a very sensitive test to quantify hydroxyl radicals and electrons produced when gold atoms, organized as nanoparticles or as a salt in solution, are irradiated by keV and MeV photons (x- and γ- rays). The crucial role of interfacial water is suggested to explain the high quantity of radicals measured for nanoparticles. These experimental data were supplemented by classical molecular dynamics simulations, revealing a specific organization of the water hydrogen bonding network at the nanoparticle surface which could be a key component in the mechanism of radical production by irradiated colloidal suspensions.
{"title":"Both experimental and molecular dynamics approaches highlight the central role of interfacial water for radical production by irradiated gold nanoparticles","authors":"Emilie Brun, Rika Tandiana, Manon Gilles, Yannis Cheref, Nguyen-Thi Van-Oanh, Carine Clavaguera, Cécile Sicard-Roselli","doi":"10.1088/1361-6455/ad2e28","DOIUrl":"https://doi.org/10.1088/1361-6455/ad2e28","url":null,"abstract":"Nanoparticles devoted to improve radiotherapy treatments are an efficient tool if they can induce the formation of deleterious species in the tumor. Their interaction with radiation is responsible for radical production but in spite of the numerous studies mostly with cells, no consensus has been reached about radical formation mechanism. In order to gain knowledge in the physico-chemical step of this phenomenon, we applied a very sensitive test to quantify hydroxyl radicals and electrons produced when gold atoms, organized as nanoparticles or as a salt in solution, are irradiated by keV and MeV photons (x- and <italic toggle=\"yes\">γ</italic>- rays). The crucial role of interfacial water is suggested to explain the high quantity of radicals measured for nanoparticles. These experimental data were supplemented by classical molecular dynamics simulations, revealing a specific organization of the water hydrogen bonding network at the nanoparticle surface which could be a key component in the mechanism of radical production by irradiated colloidal suspensions.","PeriodicalId":16826,"journal":{"name":"Journal of Physics B: Atomic, Molecular and Optical Physics","volume":"37 1","pages":""},"PeriodicalIF":1.6,"publicationDate":"2024-03-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140316246","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}
Pub Date : 2024-03-13DOI: 10.1088/1361-6455/ad2d5d
Anjali N Nair, R Arun
The entanglement dynamics of a pair of three-level V-type atoms decaying spontaneously in a common vacuum reservoir is investigated. Under the condition that the decaying transitions in the atoms have parallel dipole moments, the effect of coherences induced by spontaneous emission is considered in the atomic dynamics. We show that vacuum-induced coherence (VIC) and collective effects in atomic decay play a significant role in the creation of entanglement. By using negativity as a measure of entanglement, we study the time evolution of entanglement for initial separable and generalized Dicke states as well as maximally entangled qutrit states. We show that the effects of VIC enhance the production of entanglement from initial separable states of the atoms. We also show that the entanglement can be protected in steady-state for atoms evolving from initial entangled states. The amount of entanglement that can be preserved is more in the presence of VIC than in its absence.
研究了一对三电平 V 型原子在共同真空储层中自发衰变的纠缠动力学。在原子衰变跃迁具有平行偶极矩的条件下，原子动力学考虑了自发发射诱导的相干效应。我们表明，原子衰变中的真空诱导相干性（VIC）和集体效应在纠缠的产生中起着重要作用。通过使用负性作为纠缠度量，我们研究了初始可分离态和广义迪克态以及最大纠缠qutrit态的纠缠时间演化。我们发现，VIC 的效应增强了原子初始可分离态的纠缠生成。我们还证明，对于从初始纠缠态演化而来的原子，纠缠可以在稳态中得到保护。在有 VIC 的情况下，能保存的纠缠量比没有 VIC 的情况下更多。
{"title":"Production and protection of entanglement via vacuum induced coherences","authors":"Anjali N Nair, R Arun","doi":"10.1088/1361-6455/ad2d5d","DOIUrl":"https://doi.org/10.1088/1361-6455/ad2d5d","url":null,"abstract":"The entanglement dynamics of a pair of three-level V-type atoms decaying spontaneously in a common vacuum reservoir is investigated. Under the condition that the decaying transitions in the atoms have parallel dipole moments, the effect of coherences induced by spontaneous emission is considered in the atomic dynamics. We show that vacuum-induced coherence (VIC) and collective effects in atomic decay play a significant role in the creation of entanglement. By using negativity as a measure of entanglement, we study the time evolution of entanglement for initial separable and generalized Dicke states as well as maximally entangled qutrit states. We show that the effects of VIC enhance the production of entanglement from initial separable states of the atoms. We also show that the entanglement can be protected in steady-state for atoms evolving from initial entangled states. The amount of entanglement that can be preserved is more in the presence of VIC than in its absence.","PeriodicalId":16826,"journal":{"name":"Journal of Physics B: Atomic, Molecular and Optical Physics","volume":"63 1","pages":""},"PeriodicalIF":1.6,"publicationDate":"2024-03-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140316243","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}
Pub Date : 2024-03-12DOI: 10.1088/1361-6455/ad2e2e
Xiaoyu Liu, Zhiqiang Ji, Chenglong Wu, Shasha Li, Hong Wu, Feng Li, Yong Pu
In our work, we theoretically investigate high harmonic generation (HHG) in monolayer hexagonal indium nitride (h-InN) based on the semiconductor Bloch equation under strong laser fields. Compared with h-BN, there is no multiplateau in h-InN. This is because the intraband mechanism dominates the total HHG, and the harmonic generated by the intraband current is about three orders of magnitude higher than that generated by the interband polarization. We find that the higher order part of the HHG is mainly supplied by the interband current, which can be analyzed on the basis of the transition dipole moments between the energy bands. In addition, we found that the HHG of h-InN is sensitive to the external strains due to the modified band dispersion in the electronic structures. This study provides a useful reference for understanding the microscopic mechanism of laser-solid interaction.
{"title":"High harmonic generation in monolayer indium nitride","authors":"Xiaoyu Liu, Zhiqiang Ji, Chenglong Wu, Shasha Li, Hong Wu, Feng Li, Yong Pu","doi":"10.1088/1361-6455/ad2e2e","DOIUrl":"https://doi.org/10.1088/1361-6455/ad2e2e","url":null,"abstract":"In our work, we theoretically investigate high harmonic generation (HHG) in monolayer hexagonal indium nitride (<italic toggle=\"yes\">h</italic>-InN) based on the semiconductor Bloch equation under strong laser fields. Compared with <italic toggle=\"yes\">h</italic>-BN, there is no multiplateau in <italic toggle=\"yes\">h-</italic>InN. This is because the intraband mechanism dominates the total HHG, and the harmonic generated by the intraband current is about three orders of magnitude higher than that generated by the interband polarization. We find that the higher order part of the HHG is mainly supplied by the interband current, which can be analyzed on the basis of the transition dipole moments between the energy bands. In addition, we found that the HHG of <italic toggle=\"yes\">h</italic>-InN is sensitive to the external strains due to the modified band dispersion in the electronic structures. This study provides a useful reference for understanding the microscopic mechanism of laser-solid interaction.","PeriodicalId":16826,"journal":{"name":"Journal of Physics B: Atomic, Molecular and Optical Physics","volume":"21 1","pages":""},"PeriodicalIF":1.6,"publicationDate":"2024-03-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140316088","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}
Pub Date : 2024-03-12DOI: 10.1088/1361-6455/ad2e2b
Haozhen Li, Yang Lan, Ran Zeng, Miao Hu, Mengmeng Xu, Xiuwen Xia, Jingping Xu, Yaping Yang
Controllable single-photon scattering in a one-dimensional waveguide coupled to a Jaynes–Cummings structure containing a time-modulated two-level atom interacting with a single-mode cavity is investigated. The photon transmission and reflection amplitudes are calculated by using an effective Floquet Hamiltonian in real space. The results show that the coupling between the atom and the cavity mode can dynamically be tuned via periodically modulating the atomic transition frequency. As a consequence, the scattering behaviors of the waveguide photons can be actively manipulated, and a controllable single-photon switch with high on-off ratio could be realized. More interestingly, the switch works well within a wide frequency region, i.e., the transmission of both resonant and off-resonant waveguide photons can be effectively switched on or off with appropriate system parameters. Furthermore, the proposed dynamically tunable switching scheme is robust against atomic dissipation associated with the help of atom-cavity coupling mismatch. Such single-photon device can be used as an elementary unit for various quantum information processing.
{"title":"Controllable single-photon transport mediated by a time-modulated Jaynes–Cummings model","authors":"Haozhen Li, Yang Lan, Ran Zeng, Miao Hu, Mengmeng Xu, Xiuwen Xia, Jingping Xu, Yaping Yang","doi":"10.1088/1361-6455/ad2e2b","DOIUrl":"https://doi.org/10.1088/1361-6455/ad2e2b","url":null,"abstract":"Controllable single-photon scattering in a one-dimensional waveguide coupled to a Jaynes–Cummings structure containing a time-modulated two-level atom interacting with a single-mode cavity is investigated. The photon transmission and reflection amplitudes are calculated by using an effective Floquet Hamiltonian in real space. The results show that the coupling between the atom and the cavity mode can dynamically be tuned via periodically modulating the atomic transition frequency. As a consequence, the scattering behaviors of the waveguide photons can be actively manipulated, and a controllable single-photon switch with high on-off ratio could be realized. More interestingly, the switch works well within a wide frequency region, i.e., the transmission of both resonant and off-resonant waveguide photons can be effectively switched on or off with appropriate system parameters. Furthermore, the proposed dynamically tunable switching scheme is robust against atomic dissipation associated with the help of atom-cavity coupling mismatch. Such single-photon device can be used as an elementary unit for various quantum information processing.","PeriodicalId":16826,"journal":{"name":"Journal of Physics B: Atomic, Molecular and Optical Physics","volume":"15 1","pages":""},"PeriodicalIF":1.6,"publicationDate":"2024-03-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140316090","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}
Pub Date : 2024-03-12DOI: 10.1088/1361-6455/ad2e2c
Qingqing Wang, Pu Tu, Jinping Ma, Kaihua Shao, Xi Zhao, Baolong Xi, Yan Song, Yuren Shi
Vector gap solitons in quasi-two-dimensional Bose–Einstein condensate loaded in a square optical lattice with spin-orbit and Rabi coupling are investigated theoretically. The solitons are obtained by the Newton-Conjugate-Gradient method for various physical parameters. The stability properties of gap solitons are theoretically analyzed by direct nonlinear dynamical evolution. It is found that the existence of gap solitons is sensitive to the spin-orbit and Rabi coupling strength. Smaller Rabi coupling strength is beneficial for the excitation of solitons in the semi-infinite gap. Conversely, larger Rabi coupling strength is beneficial for the soliton excitation in the first gap. The dynamical stability of these gap solitons depends on the spin-orbit and Rabi coupling strength, and the location of the soliton in the bandgap. These findings may contribute to understanding the topological excitations in condensed matter systems.
{"title":"Vector gap solitons of spin-orbit-coupled Bose-Einstein condensate in square optical lattice","authors":"Qingqing Wang, Pu Tu, Jinping Ma, Kaihua Shao, Xi Zhao, Baolong Xi, Yan Song, Yuren Shi","doi":"10.1088/1361-6455/ad2e2c","DOIUrl":"https://doi.org/10.1088/1361-6455/ad2e2c","url":null,"abstract":"Vector gap solitons in quasi-two-dimensional Bose–Einstein condensate loaded in a square optical lattice with spin-orbit and Rabi coupling are investigated theoretically. The solitons are obtained by the Newton-Conjugate-Gradient method for various physical parameters. The stability properties of gap solitons are theoretically analyzed by direct nonlinear dynamical evolution. It is found that the existence of gap solitons is sensitive to the spin-orbit and Rabi coupling strength. Smaller Rabi coupling strength is beneficial for the excitation of solitons in the semi-infinite gap. Conversely, larger Rabi coupling strength is beneficial for the soliton excitation in the first gap. The dynamical stability of these gap solitons depends on the spin-orbit and Rabi coupling strength, and the location of the soliton in the bandgap. These findings may contribute to understanding the topological excitations in condensed matter systems.","PeriodicalId":16826,"journal":{"name":"Journal of Physics B: Atomic, Molecular and Optical Physics","volume":"15 1","pages":""},"PeriodicalIF":1.6,"publicationDate":"2024-03-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140316078","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}
Pub Date : 2024-03-06DOI: 10.1088/1361-6455/ad2e30
N I Shvetsov-Shilovski, M Lein
We apply deep learning for retrieval of the time-dependent bond length in the dissociating two-dimensional H2+ molecule using photoelectron momentum distributions. We consider a pump-probe scheme and calculate electron momentum distributions from strong-field ionization by treating the motion of the nuclei classically, semiclassically or quantum mechanically. A convolutional neural network trained on momentum distributions obtained at fixed internuclear distances retrieves the time-varying bond length with an absolute error of 0.2–0.3 a.u.
{"title":"Convolutional neural network for retrieval of the time-dependent bond length in a molecule from photoelectron momentum distributions","authors":"N I Shvetsov-Shilovski, M Lein","doi":"10.1088/1361-6455/ad2e30","DOIUrl":"https://doi.org/10.1088/1361-6455/ad2e30","url":null,"abstract":"We apply deep learning for retrieval of the time-dependent bond length in the dissociating two-dimensional H<inline-formula>\u0000<tex-math><?CDATA $_2^{+}$?></tex-math>\u0000<mml:math overflow=\"scroll\"><mml:msubsup><mml:mi></mml:mi><mml:mn>2</mml:mn><mml:mrow><mml:mo>+</mml:mo></mml:mrow></mml:msubsup></mml:math>\u0000<inline-graphic xlink:href=\"bad2e30ieqn1.gif\" xlink:type=\"simple\"></inline-graphic>\u0000</inline-formula> molecule using photoelectron momentum distributions. We consider a pump-probe scheme and calculate electron momentum distributions from strong-field ionization by treating the motion of the nuclei classically, semiclassically or quantum mechanically. A convolutional neural network trained on momentum distributions obtained at fixed internuclear distances retrieves the time-varying bond length with an absolute error of 0.2–0.3 a.u.","PeriodicalId":16826,"journal":{"name":"Journal of Physics B: Atomic, Molecular and Optical Physics","volume":"44 1","pages":""},"PeriodicalIF":1.6,"publicationDate":"2024-03-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140316087","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}
Pub Date : 2024-03-04DOI: 10.1088/1361-6455/ad2b71
Sema Caliskan, Jon Grumer, Anish M Amarsi
The lack of reliable atomic data can be a severe limitation in astrophysical modelling, in particular of events such as kilonovae that require information on all neutron-capture elements across a wide range of ionization stages. Notably, the presence of non-orthonormalities between electron orbitals representing configurations that are close in energy can introduce significant inaccuracies in computed energies and transition probabilities. Here, we propose an explicit targeted optimization (TO) method that can effectively circumvent this concern while retaining an orthonormal orbital basis set. We illustrate this method within the framework of small-scale atomic structure models of Au I, using the Grasp2018 multiconfigurational Dirac–Hartree–Fock atomic structure code. By comparing to conventional optimization schemes we show how a TO approach improves the energy level positioning and ordering. TO also leads to better agreement with experimental data for the strongest E1 transitions. This illustrates how small-scale models can be significantly improved with minor computational costs if orbital non-orthonormalities are considered carefully. These results should prove useful to multi-element atomic structure calculations in, for example, astrophysical opacity applications involving neutron-capture elements.
缺乏可靠的原子数据会严重限制天体物理建模，尤其是千新星之类的事件，因为这些事件需要在广泛的电离阶段获得所有中子捕获元素的信息。值得注意的是，代表能量接近的构型的电子轨道之间存在非正交性，会给计算能量和转变概率带来很大误差。在此，我们提出了一种明确的目标优化（TO）方法，可以有效地规避这一问题，同时保留正交轨道基集。我们利用 Grasp2018 多构型 Dirac-Hartree-Fock 原子结构代码，在 Au I 的小尺度原子结构模型框架内说明了这种方法。通过与传统优化方案的比较，我们展示了 TO 方法如何改善能级定位和排序。对于最强的 E1 转变，TO 还能更好地与实验数据保持一致。这说明了如果仔细考虑轨道的非正交性，小尺度模型是如何以较小的计算成本得到显著改进的。这些结果将被证明对涉及中子捕获元素的天体物理不透明应用等方面的多元素原子结构计算有用。
{"title":"Targeted optimization in small-scale atomic structure calculations: application to Au I","authors":"Sema Caliskan, Jon Grumer, Anish M Amarsi","doi":"10.1088/1361-6455/ad2b71","DOIUrl":"https://doi.org/10.1088/1361-6455/ad2b71","url":null,"abstract":"The lack of reliable atomic data can be a severe limitation in astrophysical modelling, in particular of events such as kilonovae that require information on all neutron-capture elements across a wide range of ionization stages. Notably, the presence of non-orthonormalities between electron orbitals representing configurations that are close in energy can introduce significant inaccuracies in computed energies and transition probabilities. Here, we propose an explicit targeted optimization (TO) method that can effectively circumvent this concern while retaining an orthonormal orbital basis set. We illustrate this method within the framework of small-scale atomic structure models of Au I, using the <sc>Grasp2018</sc> multiconfigurational Dirac–Hartree–Fock atomic structure code. By comparing to conventional optimization schemes we show how a TO approach improves the energy level positioning and ordering. TO also leads to better agreement with experimental data for the strongest E1 transitions. This illustrates how small-scale models can be significantly improved with minor computational costs if orbital non-orthonormalities are considered carefully. These results should prove useful to multi-element atomic structure calculations in, for example, astrophysical opacity applications involving neutron-capture elements.","PeriodicalId":16826,"journal":{"name":"Journal of Physics B: Atomic, Molecular and Optical Physics","volume":"216 1","pages":""},"PeriodicalIF":1.6,"publicationDate":"2024-03-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140316232","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}
京公网安备 11010802042870号
京ICP备2023020795号-1
扫码关注我们
求助内容：
应助结果提醒方式：