Daniel Plummer, Pontus Svensson, Dirk O. Gericke, Patrick Hollebon, Sam M. Vinko, Gianluca Gregori
By performing an ensemble of molecular dynamics simulations, the model-dependent ionisation state is computed for strongly interacting systems self-consistently. This is accomplished through a free energy minimisation framework based on the technique of thermodynamic integration. To illustrate the method, two simple models applicable to partially ionised hydrogen plasma are presented in which pair potentials are employed between ions and neutral particles. Within the models, electrons are either bound in the hydrogen ground state or distributed in a uniform charge-neutralising background. Particular attention is given to the transition between atomic gas and ionised plasma, where the effect of neutral interactions is explored beyond commonly used models in the chemical picture. Furthermore, pressure ionisation is observed when short range repulsion effects are included between neutrals. The developed technique is general, and we discuss the applicability to a variety of molecular dynamics models for partially ionised warm dense matter.
{"title":"Ionisation Calculations using Classical Molecular Dynamics","authors":"Daniel Plummer, Pontus Svensson, Dirk O. Gericke, Patrick Hollebon, Sam M. Vinko, Gianluca Gregori","doi":"arxiv-2409.01078","DOIUrl":"https://doi.org/arxiv-2409.01078","url":null,"abstract":"By performing an ensemble of molecular dynamics simulations, the\u0000model-dependent ionisation state is computed for strongly interacting systems\u0000self-consistently. This is accomplished through a free energy minimisation\u0000framework based on the technique of thermodynamic integration. To illustrate\u0000the method, two simple models applicable to partially ionised hydrogen plasma\u0000are presented in which pair potentials are employed between ions and neutral\u0000particles. Within the models, electrons are either bound in the hydrogen ground\u0000state or distributed in a uniform charge-neutralising background. Particular\u0000attention is given to the transition between atomic gas and ionised plasma,\u0000where the effect of neutral interactions is explored beyond commonly used\u0000models in the chemical picture. Furthermore, pressure ionisation is observed\u0000when short range repulsion effects are included between neutrals. The developed\u0000technique is general, and we discuss the applicability to a variety of\u0000molecular dynamics models for partially ionised warm dense matter.","PeriodicalId":501274,"journal":{"name":"arXiv - PHYS - Plasma Physics","volume":"66 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142196065","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
In this study, we examine thermal conductivity and the thermal Hall effect in electron-ion plasmas relevant to hot neutron stars, white dwarfs, and binary neutron star mergers, focusing on densities found in the outer crusts of neutron stars and the interiors of white dwarfs. We consider plasma consisting of single species of ions, which could be either iron $isotope[56]{Fe}$, carbon $isotope[12]{C}$, helium $isotope[4]{He}$, or hydrogen $isotope[1]{H}$ nuclei. The temperature range explored is from the melting temperature of the solid $Tsim10^9$~K up to $10^{11}$~K. This covers both degenerate and non-degenerate electron regimes. We find that thermal conductivity increases with density and temperature for which we provide analytical scaling relations valid in different regimes. The impact of magnetic fields on thermal conductivity is also analyzed, showing anisotropy in low-density regions and the presence of the thermal Hall effect characterized by Leduc-Righi coefficient. The transition from degenerate to non-degenerate regime is characterized by a minimum ratio of thermal conductivity to temperature, which is analogous to the minimum observed already in the case of electrical conductivity.
{"title":"Thermal conductivity and thermal Hall effect in dense electron-ion plasma","authors":"Arus Harutyunyan, Armen Sedrakian","doi":"arxiv-2409.01304","DOIUrl":"https://doi.org/arxiv-2409.01304","url":null,"abstract":"In this study, we examine thermal conductivity and the thermal Hall effect in\u0000electron-ion plasmas relevant to hot neutron stars, white dwarfs, and binary\u0000neutron star mergers, focusing on densities found in the outer crusts of\u0000neutron stars and the interiors of white dwarfs. We consider plasma consisting\u0000of single species of ions, which could be either iron $isotope[56]{Fe}$,\u0000carbon $isotope[12]{C}$, helium $isotope[4]{He}$, or hydrogen\u0000$isotope[1]{H}$ nuclei. The temperature range explored is from the melting\u0000temperature of the solid $Tsim10^9$~K up to $10^{11}$~K. This covers both\u0000degenerate and non-degenerate electron regimes. We find that thermal\u0000conductivity increases with density and temperature for which we provide\u0000analytical scaling relations valid in different regimes. The impact of magnetic\u0000fields on thermal conductivity is also analyzed, showing anisotropy in\u0000low-density regions and the presence of the thermal Hall effect characterized\u0000by Leduc-Righi coefficient. The transition from degenerate to non-degenerate\u0000regime is characterized by a minimum ratio of thermal conductivity to\u0000temperature, which is analogous to the minimum observed already in the case of\u0000electrical conductivity.","PeriodicalId":501274,"journal":{"name":"arXiv - PHYS - Plasma Physics","volume":"26 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142196069","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
O. Meneghini, T. Slendebroek, B. C. Lyons, K. McLaughlin, J. McClenaghan, L. Stagner, J. Harvey, T. F. Neiser, A. Ghiozzi, G. Dose, J. Guterl, A. Zalzali, T. Cote, N. Shi, D. Weisberg, S. P. Smith, B. A. Grierson, J. Candy
The Fusion Synthesis Engine (FUSE) is a state-of-the-art software suite designed to revolutionize fusion power plant design. FUSE integrates first-principle models, machine learning, and reduced models into a unified framework, enabling comprehensive simulations that go beyond traditional 0D systems studies. FUSE's modular structure supports a hierarchy of model fidelities, from steady-state to time-dependent simulations, allowing for both pre-conceptual design and operational scenario development. This framework accelerates the design process by enabling self-consistent solutions across physics, engineering, and control systems, minimizing the need for iterative expert evaluations. Leveraging modern software practices and parallel computing, FUSE also provides multi-objective optimization, balancing cost, efficiency, and operational constraints. Developed in Julia, FUSE is fully open-source under the Apache 2.0 license, promoting transparency and collaboration within the fusion research community.
{"title":"FUSE (Fusion Synthesis Engine): A Next Generation Framework for Integrated Design of Fusion Pilot Plants","authors":"O. Meneghini, T. Slendebroek, B. C. Lyons, K. McLaughlin, J. McClenaghan, L. Stagner, J. Harvey, T. F. Neiser, A. Ghiozzi, G. Dose, J. Guterl, A. Zalzali, T. Cote, N. Shi, D. Weisberg, S. P. Smith, B. A. Grierson, J. Candy","doi":"arxiv-2409.05894","DOIUrl":"https://doi.org/arxiv-2409.05894","url":null,"abstract":"The Fusion Synthesis Engine (FUSE) is a state-of-the-art software suite\u0000designed to revolutionize fusion power plant design. FUSE integrates\u0000first-principle models, machine learning, and reduced models into a unified\u0000framework, enabling comprehensive simulations that go beyond traditional 0D\u0000systems studies. FUSE's modular structure supports a hierarchy of model\u0000fidelities, from steady-state to time-dependent simulations, allowing for both\u0000pre-conceptual design and operational scenario development. This framework\u0000accelerates the design process by enabling self-consistent solutions across\u0000physics, engineering, and control systems, minimizing the need for iterative\u0000expert evaluations. Leveraging modern software practices and parallel\u0000computing, FUSE also provides multi-objective optimization, balancing cost,\u0000efficiency, and operational constraints. Developed in Julia, FUSE is fully\u0000open-source under the Apache 2.0 license, promoting transparency and\u0000collaboration within the fusion research community.","PeriodicalId":501274,"journal":{"name":"arXiv - PHYS - Plasma Physics","volume":"68 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142196072","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
We present a comparative study of copper film growth with a constant energy neutral beam, thermal evaporation, dc magnetron sputtering, high-power impulse magnetron sputtering (HiP-IMS), and bipolar HiPIMS, through molecular dynamics simulations. Experimentally determined energy distribution functions were utilized to model the deposition processes. Our results indicate significant differences in the film quality, growth rate, and substrate erosion between the various physical vapor deposition techniques. Bipolar HiPIMS shows the potential for improved film structure under certain conditions, albeit with increased substrate erosion. Bipolar +180 V HiPIMS with 10% Cu + ions exhibited the best film properties in terms of crystallinity and atomic stress among the PVD processes investigated.
我们通过分子动力学模拟对恒定能量中性束、热蒸发、直流磁控溅射、高功率脉冲磁控溅射（HiP-IMS）和双极 HiPIMS 的铜膜生长过程进行了比较研究。实验确定的能量分布函数被用来模拟沉积过程。我们的研究结果表明，各种物理气相沉积技术在薄膜质量、生长速度和基底侵蚀方面存在明显差异。双极 HiPIMS 显示出在某些条件下改善薄膜结构的潜力，尽管会增加基底侵蚀。在所研究的 PVD 过程中，使用 10% Cu + 离子的双极 +180 V HiPIMS 在结晶度和原子应力方面表现出最佳的薄膜特性。
{"title":"The role of sputtered atom and ion energy distribution in films deposited by Physical Vapor Deposition: A molecular dynamics approach","authors":"Soumya AtmaneGREMI, Maroussiak AlexandreGREMI, Amaël CaillardGREMI, Anne-Lise ThomannGREMI, Movaffaq KatebKTH, Jón Tómas GudmundssonKTH, Pascal BraultGREMI","doi":"arxiv-2409.01049","DOIUrl":"https://doi.org/arxiv-2409.01049","url":null,"abstract":"We present a comparative study of copper film growth with a constant energy\u0000neutral beam, thermal evaporation, dc magnetron sputtering, high-power impulse\u0000magnetron sputtering (HiP-IMS), and bipolar HiPIMS, through molecular dynamics\u0000simulations. Experimentally determined energy distribution functions were\u0000utilized to model the deposition processes. Our results indicate significant\u0000differences in the film quality, growth rate, and substrate erosion between the\u0000various physical vapor deposition techniques. Bipolar HiPIMS shows the\u0000potential for improved film structure under certain conditions, albeit with\u0000increased substrate erosion. Bipolar +180 V HiPIMS with 10% Cu + ions exhibited\u0000the best film properties in terms of crystallinity and atomic stress among the\u0000PVD processes investigated.","PeriodicalId":501274,"journal":{"name":"arXiv - PHYS - Plasma Physics","volume":"4 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142195848","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Being ``three-dimensional'', stellarators have the advantage that plasma currents are not essential for creating rotational-transform; however, the external current-carrying coils in stellarators are usually not planar. Reducing the inter-coil electromagnetic forces acting on strongly shaped 3D coils while preserving the favorable properties of the ``target'' magnetic field is a design challenge. In this work, we recognize that the inter-coil ${mathbf j} times {mathbf B}$ forces are the gradient of the vacuum magnetic energy, $displaystyle E := frac{1}{2mu_0}int_{R^3} !!! B^2 , dV$. We introduce an objective functional, ${cal F}equiv Phi_2 + omega E$, built on the usual quadratic flux on a prescribed target surface, $displaystyle Phi_2 := frac{1}{2}int_{cal S} ( {mathbf B} cdot {mathbf n} )^2 , dS$, and the vacuum energy, where $omega$ is a weight penalty. The Euler-Lagrange equation for stationary states is derived, and numerical illustrations are computed using the SIMSOPT code cite{simsopt}.
{"title":"Including the vacuum field energy in stellarator coil design","authors":"S. Guinchard, S. R. Hudson, E. J. Paul","doi":"arxiv-2409.01268","DOIUrl":"https://doi.org/arxiv-2409.01268","url":null,"abstract":"Being ``three-dimensional'', stellarators have the advantage that plasma\u0000currents are not essential for creating rotational-transform; however, the\u0000external current-carrying coils in stellarators are usually not planar. Reducing the inter-coil electromagnetic forces acting on strongly shaped 3D\u0000coils while preserving the favorable properties of the ``target'' magnetic\u0000field is a design challenge. In this work, we recognize that the inter-coil ${mathbf j} times {mathbf\u0000B}$ forces are the gradient of the vacuum magnetic energy, $displaystyle E :=\u0000frac{1}{2mu_0}int_{R^3} !!! B^2 , dV$. We introduce an objective functional, ${cal F}equiv Phi_2 + omega E$,\u0000built on the usual quadratic flux on a prescribed target surface,\u0000$displaystyle Phi_2 := frac{1}{2}int_{cal S} ( {mathbf B} cdot {mathbf\u0000n} )^2 , dS$, and the vacuum energy, where $omega$ is a weight penalty. The Euler-Lagrange equation for stationary states is derived, and numerical\u0000illustrations are computed using the SIMSOPT code cite{simsopt}.","PeriodicalId":501274,"journal":{"name":"arXiv - PHYS - Plasma Physics","volume":"24 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142196064","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The design of fusion devices is typically based on computationally expensive simulations. This can be alleviated using high aspect ratio models that employ a reduced number of free parameters, especially in the case of stellarator optimization where non-axisymmetric magnetic fields with a large parameter space are optimized to satisfy certain performance criteria. However, optimization is still required to find configurations with properties such as low elongation, high rotational transform, finite plasma beta, and good fast particle confinement. In this work, we train a machine learning model to construct configurations with favorable confinement properties by finding a solution to the inverse design problem, that is, obtaining a set of model input parameters for given desired properties. Since the solution of the inverse problem is non-unique, a probabilistic approach, based on mixture density networks, is used. It is shown that optimized configurations can be generated reliably using this method.
{"title":"Using Deep Learning to Design High Aspect Ratio Fusion Devices","authors":"P. Curvo, D. R. Ferreira, R. Jorge","doi":"arxiv-2409.00564","DOIUrl":"https://doi.org/arxiv-2409.00564","url":null,"abstract":"The design of fusion devices is typically based on computationally expensive\u0000simulations. This can be alleviated using high aspect ratio models that employ\u0000a reduced number of free parameters, especially in the case of stellarator\u0000optimization where non-axisymmetric magnetic fields with a large parameter\u0000space are optimized to satisfy certain performance criteria. However,\u0000optimization is still required to find configurations with properties such as\u0000low elongation, high rotational transform, finite plasma beta, and good fast\u0000particle confinement. In this work, we train a machine learning model to\u0000construct configurations with favorable confinement properties by finding a\u0000solution to the inverse design problem, that is, obtaining a set of model input\u0000parameters for given desired properties. Since the solution of the inverse\u0000problem is non-unique, a probabilistic approach, based on mixture density\u0000networks, is used. It is shown that optimized configurations can be generated\u0000reliably using this method.","PeriodicalId":501274,"journal":{"name":"arXiv - PHYS - Plasma Physics","volume":"185 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-08-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142196066","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The new class of compact quasi-axisymmetric stellarators with a wide range of field periods offers the unique potential to combine the advantages of the two leading magnetic confinement fusion devices, tokamaks and stellarators. Here we present the first numerical optimization of this class which has so far only been obtained analytically. Our approach finds significantly improved quasi-axisymmetric equilibria at aspect ratio $< 2.5$, resulting in no losses of alpha particles at reactor volume while also satisfying improved magnetohydrodynamic stability and a self-consistent plasma current.
{"title":"Exploring novel compact quasi-axisymmetric stellarators","authors":"Tobias M. Schuett, Sophia A. Henneberg","doi":"arxiv-2409.00523","DOIUrl":"https://doi.org/arxiv-2409.00523","url":null,"abstract":"The new class of compact quasi-axisymmetric stellarators with a wide range of\u0000field periods offers the unique potential to combine the advantages of the two\u0000leading magnetic confinement fusion devices, tokamaks and stellarators. Here we\u0000present the first numerical optimization of this class which has so far only\u0000been obtained analytically. Our approach finds significantly improved\u0000quasi-axisymmetric equilibria at aspect ratio $< 2.5$, resulting in no losses\u0000of alpha particles at reactor volume while also satisfying improved\u0000magnetohydrodynamic stability and a self-consistent plasma current.","PeriodicalId":501274,"journal":{"name":"arXiv - PHYS - Plasma Physics","volume":"42 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-08-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142196067","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Aman Singh Katariya, Amita Das, Animesh Sharma, Bibhuti Bhushan Sahu
Dusty plasma medium turns out to be an ideal system for studying the strongly coupled behavior of matter. The large size and slow response make their dynamics suitable to be captured through simple diagnostic tools. Furthermore, as the charge on individual particles is significantly higher than the electronic charge, the interaction amongst them can be in a strong coupling regime even at room temperatures and normal densities. Such charged dust particles are often present in several industrial plasma-based processes and can have a detrimental influence. For instance, in magnetrons, the sputtering phenomena may be affected by the accumulation of charged impurity clusters. The objective here is to understand the transport behavior of these particles in the presence of an externally applied magnetic field. For this purpose, Molecular Dynamics (MD) simulations are performed using an open-source large-scale atomic/molecular massively parallel simulator (LAMMPS). The dependence of the transport coefficient on the applied magnetic field and prevalent collisional processes has been discerned through simulations in detail.
{"title":"Diffusive transport of a 2-D magnetized dusty plasma cloud","authors":"Aman Singh Katariya, Amita Das, Animesh Sharma, Bibhuti Bhushan Sahu","doi":"arxiv-2408.16484","DOIUrl":"https://doi.org/arxiv-2408.16484","url":null,"abstract":"Dusty plasma medium turns out to be an ideal system for studying the strongly\u0000coupled behavior of matter. The large size and slow response make their\u0000dynamics suitable to be captured through simple diagnostic tools. Furthermore,\u0000as the charge on individual particles is significantly higher than the\u0000electronic charge, the interaction amongst them can be in a strong coupling\u0000regime even at room temperatures and normal densities. Such charged dust\u0000particles are often present in several industrial plasma-based processes and\u0000can have a detrimental influence. For instance, in magnetrons, the sputtering\u0000phenomena may be affected by the accumulation of charged impurity clusters. The\u0000objective here is to understand the transport behavior of these particles in\u0000the presence of an externally applied magnetic field. For this purpose,\u0000Molecular Dynamics (MD) simulations are performed using an open-source\u0000large-scale atomic/molecular massively parallel simulator (LAMMPS). The\u0000dependence of the transport coefficient on the applied magnetic field and\u0000prevalent collisional processes has been discerned through simulations in\u0000detail.","PeriodicalId":501274,"journal":{"name":"arXiv - PHYS - Plasma Physics","volume":"12 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-08-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142196073","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A constant intensity beam that propagates into a stationary plasma results in a bump-on-tail feature in velocity space. This results in an instability that transfers kinetic energy from the plasma to the electric field. We show that there are intensity profiles for the beam (found by numerical optimization) that can largely suppress this instability and drive the system into a state that, after the beam has been switched off, remains stable over long times. The modulated beam intensity requires no feedback, i.e. no knowledge of the physical system during time evolution is required, and the frequency of the modulation scales approximately inversely with system size, which is particularly favorable for large plasma systems. We also show that the results obtained are robust in the sense that perturbations, e.g. deviation from the optimized beam profiles, can be tolerated without losing the ability to suppress the instability.
{"title":"Stabilization of beam heated plasmas by beam modulation","authors":"Lukas Einkemmer","doi":"arxiv-2408.16888","DOIUrl":"https://doi.org/arxiv-2408.16888","url":null,"abstract":"A constant intensity beam that propagates into a stationary plasma results in\u0000a bump-on-tail feature in velocity space. This results in an instability that\u0000transfers kinetic energy from the plasma to the electric field. We show that\u0000there are intensity profiles for the beam (found by numerical optimization)\u0000that can largely suppress this instability and drive the system into a state\u0000that, after the beam has been switched off, remains stable over long times. The\u0000modulated beam intensity requires no feedback, i.e. no knowledge of the\u0000physical system during time evolution is required, and the frequency of the\u0000modulation scales approximately inversely with system size, which is\u0000particularly favorable for large plasma systems. We also show that the results\u0000obtained are robust in the sense that perturbations, e.g. deviation from the\u0000optimized beam profiles, can be tolerated without losing the ability to\u0000suppress the instability.","PeriodicalId":501274,"journal":{"name":"arXiv - PHYS - Plasma Physics","volume":"6 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-08-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142196071","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The average ionization state is a critical parameter in plasma models for charged particle transport, equation of state, and optical response. The dynamical or nonadiabatic Born effective charge (NBEC), calculated via first principles time-dependent density functional theory, provides exact ionic partitioning of bulk electron response for both metallic and insulating materials. The NBEC can be trivially transformed into a ''group conductivity", that is, the electron conductivity ascribed to a subset of ions. We show that for disordered metallic systems, such as warm dense matter (WDM) and hot dense plasma, the static limit of the NBEC is different from the average ionization state, but that the ionization state can be extracted from the group conductivity even in mixed systems. We demonstrate this approach using a set of archetypical examples, including cold and warm aluminium, low- and high- density WDM carbon, and a WDM carbon-beryllium-hydrogen mixture.
{"title":"Group Conductivity and Nonadiabatic Born Effective Charges of Disordered Metals, Warm Dense Matter and Hot Dense Plasma","authors":"Vidushi Sharma, Alexander J. White","doi":"arxiv-2408.16230","DOIUrl":"https://doi.org/arxiv-2408.16230","url":null,"abstract":"The average ionization state is a critical parameter in plasma models for\u0000charged particle transport, equation of state, and optical response. The\u0000dynamical or nonadiabatic Born effective charge (NBEC), calculated via first\u0000principles time-dependent density functional theory, provides exact ionic\u0000partitioning of bulk electron response for both metallic and insulating\u0000materials. The NBEC can be trivially transformed into a ''group conductivity\",\u0000that is, the electron conductivity ascribed to a subset of ions. We show that\u0000for disordered metallic systems, such as warm dense matter (WDM) and hot dense\u0000plasma, the static limit of the NBEC is different from the average ionization\u0000state, but that the ionization state can be extracted from the group\u0000conductivity even in mixed systems. We demonstrate this approach using a set of\u0000archetypical examples, including cold and warm aluminium, low- and high-\u0000density WDM carbon, and a WDM carbon-beryllium-hydrogen mixture.","PeriodicalId":501274,"journal":{"name":"arXiv - PHYS - Plasma Physics","volume":"3 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-08-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142196075","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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