Pub Date : 2024-09-20DOI: 10.1016/j.cpc.2024.109384
Robert V. Harlander , Theodoros Nellopoulos , Anton Olsson , Marius Wesle
The program ftint is introduced which numerically evaluates dimensionally regularized integrals as they occur in the perturbative approach to the gradient-flow formalism in quantum field theory. It relies on sector decomposition in order to determine the coefficients of the individual orders in , where D is the space-time dimension. For that purpose, it implements an interface to the public library pySecDec. The current version works for massive and massless integrals up to three-loop level with vanishing external momenta, but the underlying method is extendable to more general cases.
本文介绍了 ftint 程序，它可以对量子场论中梯度流形式主义的微扰方法中出现的维正则化积分进行数值评估。它依靠扇形分解来确定ϵ=(4-D)/2（其中 D 是时空维度）中各个阶的系数。当前版本适用于外部矩量消失的三环以内的大质量和无质量积分，但其基本方法可扩展到更一般的情况。
{"title":"ftint: Calculating gradient-flow integrals with pySecDec","authors":"Robert V. Harlander , Theodoros Nellopoulos , Anton Olsson , Marius Wesle","doi":"10.1016/j.cpc.2024.109384","DOIUrl":"10.1016/j.cpc.2024.109384","url":null,"abstract":"<div><div>The program <span>ftint</span> is introduced which numerically evaluates dimensionally regularized integrals as they occur in the perturbative approach to the gradient-flow formalism in quantum field theory. It relies on sector decomposition in order to determine the coefficients of the individual orders in <span><math><mi>ϵ</mi><mo>=</mo><mo>(</mo><mn>4</mn><mo>−</mo><mi>D</mi><mo>)</mo><mo>/</mo><mn>2</mn></math></span>, where <em>D</em> is the space-time dimension. For that purpose, it implements an interface to the public library <span>pySecDec</span>. The current version works for massive and massless integrals up to three-loop level with vanishing external momenta, but the underlying method is extendable to more general cases.</div></div>","PeriodicalId":285,"journal":{"name":"Computer Physics Communications","volume":"306 ","pages":"Article 109384"},"PeriodicalIF":7.2,"publicationDate":"2024-09-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142319400","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-09-20DOI: 10.1016/j.cpc.2024.109382
Joseph R. Jepson , Chris C. Hegna , Eric D. Held , Carl R. Sovinec , J. Andrew Spencer , Eric C. Howell
Herein, we formulate, analyze, and apply a numerical method for solving a Chapman-Enskog-like (CEL) continuum kinetic model for plasmas. It is shown that centering the heat flux at the beginning of the time step and the ion temperature at the end of the time step in the kinetic equation allows for a numerically-stable time advance of the coupled fluid-kinetic system. In addition, it is shown that numerical stability is impossible to achieve without explicitly enforcing key tenets of the CEL closure approach, in particular, that the number density (n), flow (u), and temperature (T) moments of the kinetic distortion remain small in time. We show that with a method to constrain these moments, it is possible to remove both the numerical growth and numerical damping from the linear modes. We apply the results from the linear stability analysis to allow for a numerically-stable fully nonlinear axisymmetric evolution of profiles in NIMROD, wherein we observe the asymptotic evolution of the flow in a DIII-D tokamak equilibrium (based on DIII-D ITER Baseline Scenario (IBS) discharge 174446 at 3390 ms). We compare the self-consistently computed results to analytics and to results from a previously benchmarked fixed-background δf implementation in NIMROD. Agreement with prediction is found for both the dynamics and asymptotics of the flow. This work demonstrates the first successful published benchmarking of the full CEL approach in a plasma fluid code.
在此，我们提出、分析并应用一种数值方法来求解等离子体的查普曼-恩斯科格（CEL）连续介质动力学模型。结果表明，在动力学方程中，以时间步开始时的热通量和时间步结束时的离子温度为中心，可以使流体-动力学耦合系统的时间推进在数值上保持稳定。此外，研究还表明，如果不明确执行 CEL 闭合方法的关键原则，特别是动能畸变的数量密度（n）、流量（u）和温度（T）时刻在时间上保持较小，就不可能实现数值稳定性。我们的研究表明，利用约束这些力矩的方法，可以消除线性模式的数值增长和数值阻尼。我们将线性稳定性分析的结果应用于 NIMROD 中完全非线性轴对称剖面的数值稳定演化，观察 DIII-D 托卡马克平衡态（基于 3390 毫秒时的 DIII-D ITER 基准方案（IBS）放电 174446）中流动的渐近演化。我们将自洽计算的结果与分析结果以及 NIMROD 中先前基准固定背景 δf 实现的结果进行了比较。结果发现，流动的动力学和渐近学都与预测一致。这项工作展示了在等离子流体代码中首次成功发布的全 CEL 方法基准。
{"title":"An analysis and successful benchmarking of the Chapman-Enskog-like (CEL) continuum kinetic closure approach algorithm in NIMROD","authors":"Joseph R. Jepson , Chris C. Hegna , Eric D. Held , Carl R. Sovinec , J. Andrew Spencer , Eric C. Howell","doi":"10.1016/j.cpc.2024.109382","DOIUrl":"10.1016/j.cpc.2024.109382","url":null,"abstract":"<div><div>Herein, we formulate, analyze, and apply a numerical method for solving a Chapman-Enskog-like (CEL) continuum kinetic model for plasmas. It is shown that centering the heat flux at the beginning of the time step and the ion temperature at the end of the time step in the kinetic equation allows for a numerically-stable time advance of the coupled fluid-kinetic system. In addition, it is shown that numerical stability is impossible to achieve without explicitly enforcing key tenets of the CEL closure approach, in particular, that the number density (<em>n</em>), flow (<strong>u</strong>), and temperature (<em>T</em>) moments of the kinetic distortion remain small in time. We show that with a method to constrain these moments, it is possible to remove both the numerical growth and numerical damping from the linear modes. We apply the results from the linear stability analysis to allow for a numerically-stable fully nonlinear axisymmetric evolution of profiles in NIMROD, wherein we observe the asymptotic evolution of the flow in a DIII-D tokamak equilibrium (based on DIII-D ITER Baseline Scenario (IBS) discharge 174446 at 3390 ms). We compare the self-consistently computed results to analytics and to results from a previously benchmarked fixed-background <em>δf</em> implementation in NIMROD. Agreement with prediction is found for both the dynamics and asymptotics of the flow. This work demonstrates the first successful published benchmarking of the full CEL approach in a plasma fluid code.</div></div>","PeriodicalId":285,"journal":{"name":"Computer Physics Communications","volume":"306 ","pages":"Article 109382"},"PeriodicalIF":7.2,"publicationDate":"2024-09-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142312514","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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 : 2024-09-20DOI: 10.1016/j.cpc.2024.109386
Souvik Bera , Tanay Pathak
We present our investigation of the study of two variable hypergeometric series, namely Appell and series, and obtain a comprehensive list of its analytic continuations enough to cover the whole real plane, except on their singular loci. We also derive analytic continuations of their 3-variable generalisation, the Lauricella series and the Lauricella-Saran series, leveraging the analytic continuations of and , which ensures that the whole real space is covered, except on the singular loci of these functions. While these studies are motivated by the frequent occurrence of these multivariable hypergeometric functions in Feynman integral evaluation, they can also be used whenever they appear in other branches of mathematical physics. To facilitate their practical use, for analytical and numerical purposes, we provide four packages: AppellF1.wl, AppellF3.wl, LauricellaFD.wl, and LauricellaSaranFS.wl in Mathematica. These packages are applicable for generic as well as non-generic values of parameters, keeping in mind their utilities in the evaluation of the Feynman integrals. We explicitly present various physical applications of these packages in the context of Feynman integral evaluation and compare the results using other packages such as FIESTA. Upon applying the appropriate conventions for numerical evaluation, we find that the results obtained from our packages are consistent. Various Mathematica notebooks demonstrating different numerical results are also provided along with this paper.
{"title":"Analytic continuations and numerical evaluation of the Appell F1, F3, Lauricella FD(3) and Lauricella-Saran FS(3) and their application to Feynman integrals","authors":"Souvik Bera , Tanay Pathak","doi":"10.1016/j.cpc.2024.109386","DOIUrl":"10.1016/j.cpc.2024.109386","url":null,"abstract":"<div><div>We present our investigation of the study of two variable hypergeometric series, namely Appell <span><math><msub><mrow><mi>F</mi></mrow><mrow><mn>1</mn></mrow></msub></math></span> and <span><math><msub><mrow><mi>F</mi></mrow><mrow><mn>3</mn></mrow></msub></math></span> series, and obtain a comprehensive list of its analytic continuations enough to cover the whole real <span><math><mo>(</mo><mi>x</mi><mo>,</mo><mi>y</mi><mo>)</mo></math></span> plane, except on their singular loci. We also derive analytic continuations of their 3-variable generalisation, the Lauricella <span><math><msubsup><mrow><mi>F</mi></mrow><mrow><mi>D</mi></mrow><mrow><mo>(</mo><mn>3</mn><mo>)</mo></mrow></msubsup></math></span> series and the Lauricella-Saran <span><math><msubsup><mrow><mi>F</mi></mrow><mrow><mi>S</mi></mrow><mrow><mo>(</mo><mn>3</mn><mo>)</mo></mrow></msubsup></math></span> series, leveraging the analytic continuations of <span><math><msub><mrow><mi>F</mi></mrow><mrow><mn>1</mn></mrow></msub></math></span> and <span><math><msub><mrow><mi>F</mi></mrow><mrow><mn>3</mn></mrow></msub></math></span>, which ensures that the whole real <span><math><mo>(</mo><mi>x</mi><mo>,</mo><mi>y</mi><mo>,</mo><mi>z</mi><mo>)</mo></math></span> space is covered, except on the singular loci of these functions. While these studies are motivated by the frequent occurrence of these multivariable hypergeometric functions in Feynman integral evaluation, they can also be used whenever they appear in other branches of mathematical physics. To facilitate their practical use, for analytical and numerical purposes, we provide four packages: <span>AppellF1.wl</span>, <span>AppellF3.wl</span>, <span>LauricellaFD.wl</span>, and <span>LauricellaSaranFS.wl</span> in <span>Mathematica</span>. These packages are applicable for generic as well as non-generic values of parameters, keeping in mind their utilities in the evaluation of the Feynman integrals. We explicitly present various physical applications of these packages in the context of Feynman integral evaluation and compare the results using other packages such as <span>FIESTA</span>. Upon applying the appropriate conventions for numerical evaluation, we find that the results obtained from our packages are consistent. Various <span>Mathematica</span> notebooks demonstrating different numerical results are also provided along with this paper.</div></div>","PeriodicalId":285,"journal":{"name":"Computer Physics Communications","volume":"306 ","pages":"Article 109386"},"PeriodicalIF":7.2,"publicationDate":"2024-09-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142359537","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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 : 2024-09-19DOI: 10.1016/j.cpc.2024.109380
Sergei Iskakov , Chia-Nan Yeh , Pavel Pokhilko , Yang Yu , Lei Zhang , Gaurav Harsha , Vibin Abraham , Ming Wen , Munkhorgil Wang , Jacob Adamski , Tianran Chen , Emanuel Gull , Dominika Zgid
The accurate ab-initio simulation of molecules and periodic solids with diagrammatic perturbation theory is an important task in quantum chemistry, condensed matter physics, and materials science. In this article, we present the WeakCoupling module of the open-source software package Green, which implements fully self-consistent diagrammatic weak coupling simulations, capable of dealing with real materials in the finite-temperature formalism. The code is licensed under the permissive MIT license. We provide self-consistent GW (scGW) and self-consistent second-order Green's function perturbation theory (GF2) solvers, analysis tools, and post-processing methods. This paper summarizes the theoretical methods implemented and provides background, tutorials and practical instructions for running simulations.
Program summary
Program Title:Green/WeakCoupling
CPC Library link to program files:https://doi.org/10.17632/2ysyhzww6t.1
Nature of problem: The simulation of periodic solids and molecules using diagrammatic perturbation theory
Solution method: We present an open-source implementation of the fully self-consistent finite-temperature many-body perturbation theory formalism at the GW and second-order perturbation theory level.
利用图解扰动理论对分子和周期性固体进行精确的非原位模拟是量子化学、凝聚态物理和材料科学领域的一项重要任务。本文介绍了开源软件包 Green 的 WeakCoupling 模块，它实现了完全自洽的图解弱耦合模拟，能够在有限温度形式主义下处理真实材料。代码采用 MIT 许可授权。我们提供自洽 GW（scGW）和自洽二阶格林函数扰动理论（GF2）求解器、分析工具和后处理方法。本文总结了所实施的理论方法，并提供了运行模拟的背景、教程和实际说明：Green/WeakCouplingCPC Library 程序文件链接：https://doi.org/10.17632/2ysyhzww6t.1Developer's repository 链接：https://github.com/Green-Phys/green-mbptProgramming 语言：C++17、CUDA、Python许可条款：MIT 许可外部例程/库：MPI >= 3.0, BLAS, Eigen >= 3.4.0, cmake >= 3.18, cuBLAS.Nature of problem: The simulation of periodic solids and molecules using diagrammatic perturbation theorySolution method：我们提出了一个在 GW 和二阶扰动理论水平上完全自洽的有限温度多体扰动理论形式主义的开源实现。
{"title":"Green/WeakCoupling: Implementation of fully self-consistent finite-temperature many-body perturbation theory for molecules and solids","authors":"Sergei Iskakov , Chia-Nan Yeh , Pavel Pokhilko , Yang Yu , Lei Zhang , Gaurav Harsha , Vibin Abraham , Ming Wen , Munkhorgil Wang , Jacob Adamski , Tianran Chen , Emanuel Gull , Dominika Zgid","doi":"10.1016/j.cpc.2024.109380","DOIUrl":"10.1016/j.cpc.2024.109380","url":null,"abstract":"<div><div>The accurate ab-initio simulation of molecules and periodic solids with diagrammatic perturbation theory is an important task in quantum chemistry, condensed matter physics, and materials science. In this article, we present the <span>WeakCoupling</span> module of the open-source software package <span>Green</span>, which implements fully self-consistent diagrammatic weak coupling simulations, capable of dealing with real materials in the finite-temperature formalism. The code is licensed under the permissive MIT license. We provide self-consistent GW (scGW) and self-consistent second-order Green's function perturbation theory (GF2) solvers, analysis tools, and post-processing methods. This paper summarizes the theoretical methods implemented and provides background, tutorials and practical instructions for running simulations.</div></div><div><h3>Program summary</h3><div><em>Program Title:</em> <span>Green</span>/<span>WeakCoupling</span></div><div><em>CPC Library link to program files:</em> <span><span>https://doi.org/10.17632/2ysyhzww6t.1</span><svg><path></path></svg></span></div><div><em>Developer's repository link:</em> <span><span>https://github.com/Green-Phys/green-mbpt</span><svg><path></path></svg></span></div><div><em>Programming language:</em> <span>C++17</span>, <span>CUDA</span>, <span>Python</span></div><div><em>Licensing provisions:</em> MIT License</div><div><em>External routines/libraries:</em> <span>MPI >= 3.0</span>, <span>BLAS</span>, <span>Eigen >= 3.4.0</span>, <span>cmake >= 3.18</span>, <span>cuBLAS</span>.</div><div><em>Nature of problem:</em> The simulation of periodic solids and molecules using diagrammatic perturbation theory</div><div><em>Solution method:</em> We present an open-source implementation of the fully self-consistent finite-temperature many-body perturbation theory formalism at the GW and second-order perturbation theory level.</div></div>","PeriodicalId":285,"journal":{"name":"Computer Physics Communications","volume":"306 ","pages":"Article 109380"},"PeriodicalIF":7.2,"publicationDate":"2024-09-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142312565","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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 : 2024-09-19DOI: 10.1016/j.cpc.2024.109385
Mustafa Kandemir , Emrah Tiras , Burcu Kirezli , İbrahim Koca
This study introduces a new Scintillator Simulation Library called SSLG4 for the Geant4 Monte Carlo simulation package. With SSLG4, we aim to enhance efficiency and accelerate progress in optical simulations within the Geant4 framework by simplifying scintillator handling and providing a rich repository of scintillators. The SSLG4 enables users to quickly include predefined scintillator materials in their simulations without requiring manual definition. The library initially contains 68 scintillators, consisting of 58 organic and 10 inorganic types. Most of these scintillators are selected from the catalogs of several scintillator manufacturers, notably Eljen and Luxium. Other scintillators are included based on their widespread use across various physics domains. The library stores optical data of scintillators in ASCII files with .mac and .txt extensions, enabling users to add, remove, or modify properties of scintillators at runtime of their applications. In addition, we made all the scintillator data available in the library on a dedicated page of our website to ensure convenient access for all users.
Program summary
Program title: SSLG4
CPC Library link to program files:https://doi.org/10.17632/3zbwr5wf7z.1
Licensing provisions: GNU General Public License 3
Programming language: C++
External routines/libraries: Geant4, CMake, OPSim
Nature of problem: Defining a new scintillator in Geant4 is a cumbersome process for some users due to three main reasons: (1) It requires a lot of data input from users, (2) collecting the scintillator data requires an extensive literature review, and (3) the collected data needs to be converted into the desired format. In addition, the interfaces provided to define a scintillator direct users to embed scintillator data into their source code, resulting in increased code complexity, reduced code readability, and an inefficient working environment.
Solution method: To solve the problems mentioned above, developing and introducing a new library consisting of fully parameterized and ready-to-use scintillators would greatly increase the useability of the Geant4 simulation package for scintillator studies and interest a wide range of scientific communities.
{"title":"SSLG4: A novel scintillator simulation library for Geant4","authors":"Mustafa Kandemir , Emrah Tiras , Burcu Kirezli , İbrahim Koca","doi":"10.1016/j.cpc.2024.109385","DOIUrl":"10.1016/j.cpc.2024.109385","url":null,"abstract":"<div><div>This study introduces a new Scintillator Simulation Library called SSLG4 for the Geant4 Monte Carlo simulation package. With SSLG4, we aim to enhance efficiency and accelerate progress in optical simulations within the Geant4 framework by simplifying scintillator handling and providing a rich repository of scintillators. The SSLG4 enables users to quickly include predefined scintillator materials in their simulations without requiring manual definition. The library initially contains 68 scintillators, consisting of 58 organic and 10 inorganic types. Most of these scintillators are selected from the catalogs of several scintillator manufacturers, notably Eljen and Luxium. Other scintillators are included based on their widespread use across various physics domains. The library stores optical data of scintillators in ASCII files with .mac and .txt extensions, enabling users to add, remove, or modify properties of scintillators at runtime of their applications. In addition, we made all the scintillator data available in the library on a dedicated page of our website to ensure convenient access for all users.</div></div><div><h3>Program summary</h3><div><em>Program title:</em> SSLG4</div><div><em>CPC Library link to program files:</em> <span><span>https://doi.org/10.17632/3zbwr5wf7z.1</span><svg><path></path></svg></span></div><div><em>Developer's repository link:</em> <span><span>https://github.com/mkandemirr/SSLG4</span><svg><path></path></svg></span>, <span><span>https://neutrino.erciyes.edu.tr/SSLG4/</span><svg><path></path></svg></span></div><div><em>Licensing provisions:</em> GNU General Public License 3</div><div><em>Programming language:</em> C++</div><div><em>External routines/libraries:</em> Geant4, CMake, OPSim</div><div><em>Nature of problem:</em> Defining a new scintillator in Geant4 is a cumbersome process for some users due to three main reasons: (1) It requires a lot of data input from users, (2) collecting the scintillator data requires an extensive literature review, and (3) the collected data needs to be converted into the desired format. In addition, the interfaces provided to define a scintillator direct users to embed scintillator data into their source code, resulting in increased code complexity, reduced code readability, and an inefficient working environment.</div><div><em>Solution method:</em> To solve the problems mentioned above, developing and introducing a new library consisting of fully parameterized and ready-to-use scintillators would greatly increase the useability of the Geant4 simulation package for scintillator studies and interest a wide range of scientific communities.</div></div>","PeriodicalId":285,"journal":{"name":"Computer Physics Communications","volume":"306 ","pages":"Article 109385"},"PeriodicalIF":7.2,"publicationDate":"2024-09-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142312564","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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 : 2024-09-19DOI: 10.1016/j.cpc.2024.109381
Gang Cui, Kai Jiang, Tiejun Zhou
In this work, we propose an efficient nullspace-preserving saddle search (NPSS) method for a class of phase transitions involving translational invariance, where the critical states are often degenerate. The NPSS method includes two stages, escaping from the basin and searching for the index-1 generalized saddle point. The NPSS method climbs upward from the generalized local minimum in segments to overcome the challenges of degeneracy. In each segment, an effective ascent direction is ensured by keeping this direction orthogonal to the nullspace of the initial state in this segment. This method can escape the basin quickly and converge to the transition states efficiently. We apply the NPSS method to the phase transitions between crystals, and between crystal and quasicrystal, based on the Landau-Brazovskii and Lifshitz-Petrich free energy functionals. Numerical results show a good performance of the NPSS method.
{"title":"An efficient saddle search method for ordered phase transitions involving translational invariance","authors":"Gang Cui, Kai Jiang, Tiejun Zhou","doi":"10.1016/j.cpc.2024.109381","DOIUrl":"10.1016/j.cpc.2024.109381","url":null,"abstract":"<div><p>In this work, we propose an efficient nullspace-preserving saddle search (NPSS) method for a class of phase transitions involving translational invariance, where the critical states are often degenerate. The NPSS method includes two stages, escaping from the basin and searching for the index-1 generalized saddle point. The NPSS method climbs upward from the generalized local minimum in segments to overcome the challenges of degeneracy. In each segment, an effective ascent direction is ensured by keeping this direction orthogonal to the nullspace of the initial state in this segment. This method can escape the basin quickly and converge to the transition states efficiently. We apply the NPSS method to the phase transitions between crystals, and between crystal and quasicrystal, based on the Landau-Brazovskii and Lifshitz-Petrich free energy functionals. Numerical results show a good performance of the NPSS method.</p></div>","PeriodicalId":285,"journal":{"name":"Computer Physics Communications","volume":"306 ","pages":"Article 109381"},"PeriodicalIF":7.2,"publicationDate":"2024-09-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142274405","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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}
We have developed a theoretical framework MemriSim for simulating the resistive switching behaviors of oxide memristors. MemriSim comprises two major parts, i) structural evolution of oxygen vacancies during conductive filament formation/rupture by kinetic Monte Carlo (kMC) algorithm, and ii) transport calculations based on the scenario of electron tunneling and thermionic emission with the kMC derived structures. As prototype probes, we have computed the current-voltage (I-V) curves of HfO2 and TaOx based memristors and compared the results with experimental measurements, which show perfect agreement. By tuning the physical parameters, MemriSim can describe resistive switching devices with different oxide layers and metal electrodes. In addition, the pulse transient current can also be simulated by considering the transient response of RLC circuit. The developed framework not only provides a general approach for understanding the fundamental mechanism of resistive switching in oxides, but also opens up new opportunities for designing and optimizing memristor-based architectures for nonvolatile memory, logic-in-memory and neuromorphic computing.
Program summary
Program Title: MemriSim.
CPC Library link to program files: https://doi.org/10.17632/8gbbgf8z49.1
Licensing provisions: GPLv2.
Programming language: C++.
Supplementary material: Supplementary material is available.
Nature of problem: A general framework for simulating the resistive switching properties of oxide-based memristors; generate the structure of oxide layer during filament formation/rupture; calculate the I-V curves of memristive device; simulate the pulse transient current; predict the resistive switching performance of new devices.
Solution method: The framework uses kMC algorithm for structural evolution, the electric field inside oxide layer is computed by the Poisson's equation, and the transport calculation is based on electron tunneling and thermionic emission.
{"title":"MemriSim: A theoretical framework for simulating electron transport in oxide memristors","authors":"Shuwei Zhai , Wenjin Gao , Guoxiang Zhi , Tianzhao Li , Wenzhen Dou , Miao Zhou","doi":"10.1016/j.cpc.2024.109375","DOIUrl":"10.1016/j.cpc.2024.109375","url":null,"abstract":"<div><div>We have developed a theoretical framework MemriSim for simulating the resistive switching behaviors of oxide memristors. MemriSim comprises two major parts, i) structural evolution of oxygen vacancies during conductive filament formation/rupture by kinetic Monte Carlo (kMC) algorithm, and ii) transport calculations based on the scenario of electron tunneling and thermionic emission with the kMC derived structures. As prototype probes, we have computed the current-voltage (I-V) curves of HfO<sub>2</sub> and TaO<sub>x</sub> based memristors and compared the results with experimental measurements, which show perfect agreement. By tuning the physical parameters, MemriSim can describe resistive switching devices with different oxide layers and metal electrodes. In addition, the pulse transient current can also be simulated by considering the transient response of RLC circuit. The developed framework not only provides a general approach for understanding the fundamental mechanism of resistive switching in oxides, but also opens up new opportunities for designing and optimizing memristor-based architectures for nonvolatile memory, logic-in-memory and neuromorphic computing.</div><div>Program summary</div><div>Program Title: MemriSim.</div><div>CPC Library link to program files: <span><span>https://doi.org/10.17632/8gbbgf8z49.1</span><svg><path></path></svg></span></div><div>Licensing provisions: GPLv2.</div><div>Programming language: C++.</div><div>Supplementary material: Supplementary material is available.</div><div>Nature of problem: A general framework for simulating the resistive switching properties of oxide-based memristors; generate the structure of oxide layer during filament formation/rupture; calculate the I-V curves of memristive device; simulate the pulse transient current; predict the resistive switching performance of new devices.</div><div>Solution method: The framework uses kMC algorithm for structural evolution, the electric field inside oxide layer is computed by the Poisson's equation, and the transport calculation is based on electron tunneling and thermionic emission.</div></div>","PeriodicalId":285,"journal":{"name":"Computer Physics Communications","volume":"306 ","pages":"Article 109375"},"PeriodicalIF":7.2,"publicationDate":"2024-09-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142312563","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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 : 2024-09-13DOI: 10.1016/j.cpc.2024.109378
Georges Sadaka , Pierre Jolivet , Efstathios G. Charalampidis , Ionut Danaila
<div><p>We present and distribute a parallel finite-element toolbox written in the free software <span>FreeFEM</span> for computing the Bogoliubov-de Gennes (BdG) spectrum of stationary solutions to one- and two-component Gross-Pitaevskii (GP) equations, in two or three spatial dimensions. The parallelization of the toolbox relies exclusively upon the recent interfacing of <span>FreeFEM</span> with the <span>PETSc</span> library. The latter contains itself a wide palette of state-of-the-art linear algebra libraries, graph partitioners, mesh generation and domain decomposition tools, as well as a suite of eigenvalue solvers that are embodied in the <span>SLEPc</span> library. Within the present toolbox, stationary states of the GP equations are computed by a Newton method. Branches of solutions are constructed using an adaptive step-size continuation algorithm. The combination of mesh adaptivity tools from <span>FreeFEM</span> with the parallelization features from <span>PETSc</span> makes the toolbox efficient and reliable for the computation of stationary states. Their BdG spectrum is computed using the <span>SLEPc</span> eigenvalue solver. We perform extensive tests and validate our programs by comparing the toolbox's results with known theoretical and numerical findings that have been reported in the literature.</p></div><div><h3>Program summary</h3><p><em>Program Title:</em> FFEM_BdG_ddm_toolbox.zip</p><p><em>CPC Library link to program files:</em> <span><span>https://doi.org/10.17632/w9hg964wpb.1</span><svg><path></path></svg></span></p><p><em>Licensing provisions:</em> GPLv3</p><p><em>Programming language:</em> <span>FreeFEM</span> (v 4.12) free software (<span><span>www.freefem.org</span><svg><path></path></svg></span>)</p><p><em>Nature of problem:</em> Among the plethora of configurations that may exist in Gross-Pitaevskii (GP) equations modeling one or two-component Bose-Einstein condensates, only the ones that are deemed spectrally stable (or even, in some cases, weakly unstable) have high probability to be observed in realistic ultracold atoms experiments. To investigate the spectral stability of solutions requires the numerical study of the linearization of GP equations, the latter commonly known as the Bogoliubov-de Gennes (BdG) spectral problem. The present software offers an efficient and reliable tool for the computation of eigenvalues (or modes) of the BdG problem for a given two- or three-dimensional GP configuration. Then, the spectral stability (or instability) can be inferred from its spectrum, thus predicting (or not) its observability in experiments.</p><p><em>Solution method:</em> The present toolbox in <span>FreeFEM</span> consists of the following steps. At first, the GP equations in two (2D) and three (3D) spatial dimensions are discretized by using P2 (piece-wise quadratic) Galerkin triangular (in 2D) or tetrahedral (in 3D) finite elements. For a given configuration of interest, mesh adaptivity in <span>FreeFEM</span>
我们介绍并发布了一个用免费软件 FreeFEM 编写的并行有限元工具箱，用于计算二维或三维空间中单分量和双分量格罗斯-皮塔耶夫斯基（GP）方程静态解的波哥留布夫-德-吉尼斯（BdG）谱。工具箱的并行化完全依赖于 FreeFEM 与 PETSc 库的最新接口。PETSc 库本身包含大量最先进的线性代数库、图形分割器、网格生成和域分解工具，以及 SLEPc 库中的一套特征值求解器。在本工具箱中，GP 方程的静止状态是通过牛顿法计算得出的。使用自适应步长延续算法构建求解分支。FreeFEM 的网格自适应工具与 PETSc 的并行化功能相结合，使得该工具箱在计算静止状态时高效可靠。它们的 BdG 频谱是使用 SLEPc 特征值求解器计算的。我们通过比较工具箱的结果与文献中报道的已知理论和数值结果，对程序进行了广泛的测试和验证：FFEM_BdG_ddm_toolbox.zipCPC 库链接到程序文件：https://doi.org/10.17632/w9hg964wpb.1Licensing 规定：GPLv3编程语言：FreeFEM (v 4.12) 免费软件 (www.freefem.org)问题性质：在模拟单组分或双组分玻色-爱因斯坦凝聚体的格罗斯-皮塔耶夫斯基（Gross-Pitaevskii，GP）方程中可能存在的大量构型中，只有那些被认为具有光谱稳定性（甚至在某些情况下具有弱不稳定性）的构型才极有可能在现实的超冷原子实验中被观测到。要研究解的光谱稳定性，需要对 GP 方程的线性化进行数值研究，后者通常被称为波哥留布夫-德-吉恩（Bogoliubov-de Gennes，BdG）光谱问题。本软件为计算给定二维或三维 GP 配置的 BdG 问题特征值（或模式）提供了高效可靠的工具。然后，可以根据其频谱推断其频谱稳定性（或不稳定性），从而预测（或不预测）其在实验中的可观测性：FreeFEM 中的本工具箱包括以下步骤。首先，使用 P2（片断二次方）Galerkin 三角形（二维）或四面体（三维）有限元对二维（2D）和三维（3D）空间的 GP 方程进行离散化。对于给定的相关配置，FreeFEM 中的网格自适应功能可缩小问题的规模，从而减少工具箱的执行时间。然后，通过牛顿方法获得 GP 方程的静态，该方法的主干是从 PETSc1 库中精挑细选的可靠、高效的线性求解器。在确定静态配置后，采用参数延续法对 GP 方程中的化学势（有效控制 BEC 中的原子数）进行延续，并对延续参数进行步长调整，以追踪此类解的分支。最后，通过使用 SLEPc2 库精确求解参数空间中每一点的基本特征值问题，计算解分支的稳定性（即 BdG 频谱）。本工具箱采用域分解法（DDM）进行三维计算。在计算过程中，工具箱不仅存储解，还存储从 BdG 问题解中产生的特征值和各自的特征向量。我们提供了在单分量和双分量 GP 方程中计算静态配置及其 BdG 频谱的示例：运行时间：几分钟到几小时不等，取决于网格分辨率和空间维度。
{"title":"Parallel finite-element codes for the Bogoliubov-de Gennes stability analysis of Bose-Einstein condensates","authors":"Georges Sadaka , Pierre Jolivet , Efstathios G. Charalampidis , Ionut Danaila","doi":"10.1016/j.cpc.2024.109378","DOIUrl":"10.1016/j.cpc.2024.109378","url":null,"abstract":"<div><p>We present and distribute a parallel finite-element toolbox written in the free software <span>FreeFEM</span> for computing the Bogoliubov-de Gennes (BdG) spectrum of stationary solutions to one- and two-component Gross-Pitaevskii (GP) equations, in two or three spatial dimensions. The parallelization of the toolbox relies exclusively upon the recent interfacing of <span>FreeFEM</span> with the <span>PETSc</span> library. The latter contains itself a wide palette of state-of-the-art linear algebra libraries, graph partitioners, mesh generation and domain decomposition tools, as well as a suite of eigenvalue solvers that are embodied in the <span>SLEPc</span> library. Within the present toolbox, stationary states of the GP equations are computed by a Newton method. Branches of solutions are constructed using an adaptive step-size continuation algorithm. The combination of mesh adaptivity tools from <span>FreeFEM</span> with the parallelization features from <span>PETSc</span> makes the toolbox efficient and reliable for the computation of stationary states. Their BdG spectrum is computed using the <span>SLEPc</span> eigenvalue solver. We perform extensive tests and validate our programs by comparing the toolbox's results with known theoretical and numerical findings that have been reported in the literature.</p></div><div><h3>Program summary</h3><p><em>Program Title:</em> FFEM_BdG_ddm_toolbox.zip</p><p><em>CPC Library link to program files:</em> <span><span>https://doi.org/10.17632/w9hg964wpb.1</span><svg><path></path></svg></span></p><p><em>Licensing provisions:</em> GPLv3</p><p><em>Programming language:</em> <span>FreeFEM</span> (v 4.12) free software (<span><span>www.freefem.org</span><svg><path></path></svg></span>)</p><p><em>Nature of problem:</em> Among the plethora of configurations that may exist in Gross-Pitaevskii (GP) equations modeling one or two-component Bose-Einstein condensates, only the ones that are deemed spectrally stable (or even, in some cases, weakly unstable) have high probability to be observed in realistic ultracold atoms experiments. To investigate the spectral stability of solutions requires the numerical study of the linearization of GP equations, the latter commonly known as the Bogoliubov-de Gennes (BdG) spectral problem. The present software offers an efficient and reliable tool for the computation of eigenvalues (or modes) of the BdG problem for a given two- or three-dimensional GP configuration. Then, the spectral stability (or instability) can be inferred from its spectrum, thus predicting (or not) its observability in experiments.</p><p><em>Solution method:</em> The present toolbox in <span>FreeFEM</span> consists of the following steps. At first, the GP equations in two (2D) and three (3D) spatial dimensions are discretized by using P2 (piece-wise quadratic) Galerkin triangular (in 2D) or tetrahedral (in 3D) finite elements. For a given configuration of interest, mesh adaptivity in <span>FreeFEM</span> ","PeriodicalId":285,"journal":{"name":"Computer Physics Communications","volume":"306 ","pages":"Article 109378"},"PeriodicalIF":7.2,"publicationDate":"2024-09-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142243052","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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 : 2024-09-13DOI: 10.1016/j.cpc.2024.109379
Roman Čurík , Jiří Horáček
Numerical analytical continuation of a function is used to determine its complex roots. The analytical continuation is carried out by means of a barycentric formula. From the knowledge of the complex roots the energy and width of shape resonances as well as of quantum virtual states can be determined. The roots are calculated for several realistic models and the results are compared with other approaches. We also explore and discuss a stability of the predicted resonant roots with respect to changes of the perturbation potential.
{"title":"Determination of electronic resonances by analytic continuation using barycentric formula","authors":"Roman Čurík , Jiří Horáček","doi":"10.1016/j.cpc.2024.109379","DOIUrl":"10.1016/j.cpc.2024.109379","url":null,"abstract":"<div><p>Numerical analytical continuation of a function is used to determine its complex roots. The analytical continuation is carried out by means of a barycentric formula. From the knowledge of the complex roots the energy and width of shape resonances as well as of quantum virtual states can be determined. The roots are calculated for several realistic models and the results are compared with other approaches. We also explore and discuss a stability of the predicted resonant roots with respect to changes of the perturbation potential.</p></div>","PeriodicalId":285,"journal":{"name":"Computer Physics Communications","volume":"306 ","pages":"Article 109379"},"PeriodicalIF":7.2,"publicationDate":"2024-09-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142243049","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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}
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