Computer Physics Communications最新文献

{"title":"GridapROMs.jl: Efficient reduced order modelling in the Julia programming language","authors":"Nicholas Mueller,&nbsp;Santiago Badia","doi":"10.1016/j.cpc.2025.109985","DOIUrl":"10.1016/j.cpc.2025.109985","url":null,"abstract":"<div><div>In this paper, we introduce GridapROMs, a Julia-based library for the numerical approximation of parameterized partial differential equations (PDEs) using a comprehensive suite of linear reduced order models (ROMs). The library is designed to be extendable and productive, leveraging an expressive high-level API built on the Gridap PDE solver backend, while achieving high performance through Julia’s just-in-time compiler and advanced lazy evaluation techniques. GridapROMs is PDE-agnostic, enabling its application to a wide range of problems, including linear, nonlinear, single-field, multi-field, steady, and unsteady equations. This work details the library’s key innovations, implementation principles, and core components, providing usage examples and demonstrating its capabilities by solving a fluid dynamics problem modeled by the Navier-Stokes equations in a 3D geometry. <strong>Program summary</strong> <em>Program Title:</em> GridapROMs.jl (version 1.0) <em>CPC Library link to program files:</em> <span><span>https://doi.org/10.17632/h27nszy8bt.1</span><svg><path></path></svg></span> <em>Developer’s repository link:</em> <span><span>https://github.com/Gridap/GridapROMs.jl</span><svg><path></path></svg></span> <em>Licensing provisions:</em> MIT license <em>Programming language:</em> Julia <em>Nature of problem:</em> Numerical simulation of parameterized PDEs, including linear, nonlinear, single-field, multi-field, steady, and unsteady problems. Classical full-order models are computationally expensive, requiring intensive computations for each parameter configuration. <em>Solution method:</em> GridapROMs approximates the parameter-to-solution map using linear reduced order models. It constructs a reduced basis from the tangent hyperplane to the solution manifold and applies a (Petrov-)Galerkin projection to the full-order equations. Nonaffine parameter dependencies in the residual and/or Jacobian are efficiently handled using hyper-reduction techniques.</div></div>","PeriodicalId":285,"journal":{"name":"Computer Physics Communications","volume":"320 ","pages":"Article 109985"},"PeriodicalIF":3.4,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145786465","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}

{"title":"Digifrac: Reconstruction and quantification of discrete fractures in rocks using micro-CT images","authors":"Lianhe Sun ,&nbsp;Bin Wang ,&nbsp;Yaochen Zhang ,&nbsp;Jiacheng Jin ,&nbsp;Zelong Mao ,&nbsp;Haizhu Wang ,&nbsp;Mao Sheng ,&nbsp;Bing Yang ,&nbsp;Sergey Stanchits ,&nbsp;Alexey Cheremisin","doi":"10.1016/j.cpc.2025.109962","DOIUrl":"10.1016/j.cpc.2025.109962","url":null,"abstract":"<div><div>Fractures in rock masses are a central focus in research areas such as unconventional energy extraction, nuclear waste disposal, and carbon sequestration. Laboratory investigations of fracture parameters are essential for optimizing field operations. In recent years, CT scanning has emerged as a widely adopted non-destructive inspection technique. However, existing methods for post-processing CT scan data face persistent challenges in achieving high accuracy and efficiency. To address these challenges, we propose a novel Python-based post-processing framework that integrates a slice-by-slice thinning algorithm, local thickness computation, and point cloud data processing techniques. This framework enables precise characterization of fractured digital rocks by quantifying fracture width distribution and fracture surface orientation, alongside standard structural evaluation metrics such as the fractal dimension, volume ratio, and the H-index. Its feasibility, accuracy, and flexibility are validated through analyses of diverse fracturing samples, including fluid-fractured samples, shear-induced fracture samples, and samples containing multiple secondary fractures. <strong>PROGRAM SUMMARY</strong> <em>Program title</em>:Digifrac <em>CPC Library link to program files</em>: <span><span>https://10.17632/hcynpd9hf4.1</span><svg><path></path></svg></span> <em>Developer’s repository link</em>: <span><span>https://github.com/BinWang0213/DigiFrac</span><svg><path></path></svg></span> <em>Licensing provisions</em>: GPLv3 <em>Programming language</em>: Python <em>Nature of problem</em>: This program quantitatively calculates the three-dimensional structural parameters of fracture networks in rocks based on CT scan data. In addition to basic parameters such as fractal dimension, fracture volume, and surface area, it also provides accurate determinations of fracture width distribution and fracture surface orientation. <em>Solution method</em>: The random forest algorithm is employed to improve the accuracy of CT data segmentation, while a slice-by-slice thinning algorithm is used to extract the fracture medial surface, thereby enhancing the precision of fracture aperture distribution calculations. Furthermore, the three-dimensional orientation distribution of fractures is determined from the 3D point cloud data of the extracted medial surface.</div></div>","PeriodicalId":285,"journal":{"name":"Computer Physics Communications","volume":"320 ","pages":"Article 109962"},"PeriodicalIF":3.4,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145616214","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}

{"title":"Corrigendum to “SimpleBounce: A simple package for the false vacuum decay” [Computer Physics Communications 258 (2021) 107566]","authors":"Ryosuke Sato","doi":"10.1016/j.cpc.2025.110006","DOIUrl":"10.1016/j.cpc.2025.110006","url":null,"abstract":"","PeriodicalId":285,"journal":{"name":"Computer Physics Communications","volume":"320 ","pages":"Article 110006"},"PeriodicalIF":3.4,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145880065","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}

{"title":"QR2-code: An open-source program for double resonance Raman spectra","authors":"Jianqi Huang ,&nbsp;Renhui Liu ,&nbsp;Ye Zhang ,&nbsp;Nguyen Tuan Hung ,&nbsp;Huaihong Guo ,&nbsp;Riichiro Saito ,&nbsp;Teng Yang","doi":"10.1016/j.cpc.2025.110005","DOIUrl":"10.1016/j.cpc.2025.110005","url":null,"abstract":"<div><div>We present an open-source program <span>QR²-code</span> that computes double-resonance Raman (DRR) spectra using first-principles calculations. <span>QR²-code</span> can calculate not only two-phonon DRR spectra but also single-resonance Raman spectra and defect-induced DRR spectra. For defect-induced DRR spectra, we simply assume that the electron-defect matrix element of elastic scattering is a constant. Hands-on tutorials for graphene are given to show how to run <span>QR²-code</span> for single-resonance, double-resonance, and defect-induced Raman spectra. We also compare the single-resonance Raman spectra by <span>QR²-code</span> with that by <span>QERaman</span> code. In <span>QR²-code</span>, the Raman spectrum is calculated by the time-dependent perturbation theory, in which the energy dispersions of electron and phonon are taken from <span>Quantum ESPRESSO</span> (<span>QE</span>) code and the electron-phonon matrix element is obtained from the modified Electron-Phonon-Wannier (<span>EPW</span>) code. All codes, examples, and scripts are available on the GitHub repository.</div><div><strong>Program Summary</strong></div><div><em>Program Title:</em> <span>QR²-code</span></div><div><em>CPC Library link to program files:</em> <span><span>https://doi.org/10.17632/vstc3hx5bs.1</span><svg><path></path></svg></span></div><div><em>Developer’s repository link:</em> <span><span>https://github.com/JoeyyHuang/QR2-code</span><svg><path></path></svg></span></div><div><em>Licensing provisions:</em> GNU General Public Licence 3.0</div><div><em>Programming language:</em> Fortran</div><div><em>External routines</em>: <span>Quantum ESPRESSO v7.3.1</span>, <span>EPW v5.8.1</span></div><div><em>Nature of problem:</em>Single-resonance, double-resonance, and defect-induced Raman spectra with first-principles calculations.</div><div><em>Solution method:</em>The Raman spectrum is calculated by the time-dependent perturbation theory, in which the energy dispersions of electron and phonon and electron-phonon matrix elements are obtained from the <span>Quantum ESPRESSO</span> and modified <span>EPW</span> codes. <em>Supplementary material:</em> <span><span>http://qr2-code.com</span><svg><path></path></svg></span></div></div>","PeriodicalId":285,"journal":{"name":"Computer Physics Communications","volume":"320 ","pages":"Article 110005"},"PeriodicalIF":3.4,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145880068","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}

{"title":"SOFIA: Singularities of Feynman integrals automatized","authors":"Miguel Correia ,&nbsp;Mathieu Giroux ,&nbsp;Sebastian Mizera","doi":"10.1016/j.cpc.2025.109970","DOIUrl":"10.1016/j.cpc.2025.109970","url":null,"abstract":"<div><div>We introduce <figure><img></figure>, a <span>Mathematica</span> package that automatizes the computation of singularities of Feynman integrals, based on new theoretical understanding of their analytic structure. Given a Feynman diagram, <figure><img></figure>generates a list of potential singularities along with a candidate symbol alphabet. The package also provides a comprehensive set of tools for analyzing the analytic properties of Feynman integrals and related objects, such as cosmological and energy correlators. We showcase its capabilities by reproducing known results and predicting singularities and symbol alphabets of Feynman integrals at and beyond the high-precision frontier.</div></div><div><h3>Program Summary</h3><div><em>Program title</em>: <span>SOFIA</span> (Singularities of Feynman Integrals Automatized)</div><div><em>CPC Library link to program files:</em> <span><span>https://doi.org/10.17632/3nnz2mr5wx.1</span><svg><path></path></svg></span></div><div><em>Developer’s repository link</em>: <span><span>https://github.com/StrangeQuark007/SOFIA</span><svg><path></path></svg></span> [1]</div><div><em>Licensing provisions</em>: MIT license</div><div><em>Programming language</em>: <span>Mathematica</span> 13 or higher</div><div><em>Supplementary material</em>: The example file <span>SOFIA_examples.nb</span> in SOFIA GitHub <span><span>[1]</span></span>.</div><div><em>Nature of problem</em>: This paper makes a significant contribution to perturbative computations in particle physics and related fields, by introducing a novel computer package analyzing the singularity structure of these integrals. In practice, this information can be leveraged to derive differential equations, the solutions of which enable efficient computation of the Feynman integrals, a crucial step that has been a major bottleneck in high-precision QCD computations. We believe this paper pushes the field of Feynman integrals into a new direction. The key insights that enabled this work were based on applications of cutting-edge techniques from algebraic geometry. The versatility of the package we introduce means it can be also used in other applications, including computations of cosmological and energy-energy correlators, as well as post-Minkowski expansion of gravitational potentials.</div><div><em>Solution method</em>: Based on new theoretical insights, it provides an easy-to-use open-source tool for multi-loop computations in perturbation theory. In the paper, we demonstrated it can be used in diverse applications, including perturbative Standard Model computations, computations of cosmological and energy-energy correlators, as well as post-Minkowski expansions of gravitational potentials. Given the high degree of automation and broad scope of applications, we think the paper would be a good fit in CPC.</div></div>","PeriodicalId":285,"journal":{"name":"Computer Physics Communications","volume":"320 ","pages":"Article 109970"},"PeriodicalIF":3.4,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145880070","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}

{"title":"Simulating non-brownian suspensions with non-homogeneous Navier slip boundary conditions","authors":"Daniela Moreno-Chaparro ,&nbsp;Florencio Balboa Usabiaga ,&nbsp;Nicolas Moreno ,&nbsp;Marco Ellero","doi":"10.1016/j.cpc.2025.109947","DOIUrl":"10.1016/j.cpc.2025.109947","url":null,"abstract":"<div><div>Fluid-structure interactions are commonly modeled using no-slip boundary conditions. However, small deviations from these conditions can significantly alter the dynamics of suspensions and particles, especially at the micro and nano scales. This work presents a robust implicit solvent method for simulating non-colloidal suspensions with non-homogeneous Navier slip boundary conditions. Our approach is based on a regularized boundary integral formulation, enabling accurate and efficient computation of hydrodynamic interactions. This makes the method well-suited for large-scale simulations. We validate the method by comparing computed drag forces on homogeneous and Janus particles with analytical results. Additionally, we consider the effective viscosity of suspensions with varying slip lengths, benchmarking against available analytical no-slip and partial-slip theories.</div></div>","PeriodicalId":285,"journal":{"name":"Computer Physics Communications","volume":"320 ","pages":"Article 109947"},"PeriodicalIF":3.4,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145616113","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}

{"title":"XtalOpt version 14: Variable-composition crystal structure search for functional materials through Pareto optimization","authors":"Samad Hajinazar,&nbsp;Eva Zurek","doi":"10.1016/j.cpc.2025.109910","DOIUrl":"10.1016/j.cpc.2025.109910","url":null,"abstract":"&lt;div&gt;&lt;div&gt;Version 14 of &lt;span&gt;XtalOpt&lt;/span&gt;, an evolutionary multi-objective global optimization algorithm for crystal structure prediction, is now available for download from its official website &lt;span&gt;&lt;span&gt;https://xtalopt.github.io&lt;/span&gt;&lt;svg&gt;&lt;path&gt;&lt;/path&gt;&lt;/svg&gt;&lt;/span&gt;, and the Computer Physics Communications Library. The new version of the code is designed to perform a ground state search for crystal structures with variable compositions by integrating a suite of &lt;em&gt;ab initio&lt;/em&gt; methods alongside classical and machine-learning potentials for structural relaxation. The multi-objective search framework has been enhanced through the introduction of Pareto optimization, enabling efficient discovery of functional materials. Herein, we describe the newly implemented methodologies, provide detailed instructions for their use, and present an overview of additional improvements included in the latest version of the code.&lt;/div&gt;&lt;div&gt;&lt;strong&gt;NEW VERSION PROGRAM SUMMARY&lt;/strong&gt; &lt;em&gt;Program Title:&lt;/em&gt; XtalOpt &lt;em&gt;CPC Library link to program files:&lt;/em&gt; &lt;span&gt;&lt;span&gt;https://doi.org/10.17632/jt5pvnnm39.5&lt;/span&gt;&lt;svg&gt;&lt;path&gt;&lt;/path&gt;&lt;/svg&gt;&lt;/span&gt;&lt;/div&gt;&lt;div&gt;&lt;em&gt;Developer’s repository link:&lt;/em&gt; &lt;span&gt;&lt;span&gt;https://github.com/xtalopt/XtalOpt&lt;/span&gt;&lt;svg&gt;&lt;path&gt;&lt;/path&gt;&lt;/svg&gt;&lt;/span&gt;&lt;/div&gt;&lt;div&gt;&lt;em&gt;Code Ocean capsule:&lt;/em&gt; (to be added by Technical Editor)&lt;/div&gt;&lt;div&gt;&lt;em&gt;Licensing provisions:&lt;/em&gt; 3-clause/BSD.&lt;/div&gt;&lt;div&gt;&lt;em&gt;Programming language:&lt;/em&gt; C++. &lt;em&gt;Journal reference of previous version:&lt;/em&gt; Computer Physics Communications 304 (2024) 109306. &lt;em&gt;Does the new version supersede the previous version?:&lt;/em&gt; Yes.&lt;/div&gt;&lt;div&gt;&lt;em&gt;Reasons for the new version:&lt;/em&gt; Implementation of the variable-composition evolutionary search feature and Pareto optimization within the &lt;span&gt;XtalOpt&lt;/span&gt; program package.&lt;/div&gt;&lt;div&gt;&lt;em&gt;Summary of revisions:&lt;/em&gt; Implemented evolutionary global optimization of structures with variable compositions, the Pareto algorithm for multi-objective optimization, and the multi-cut crossover operation. Various improvements have been made to the user interface, and bugs have been fixed.&lt;/div&gt;&lt;div&gt;&lt;em&gt;Nature of problem:&lt;/em&gt; For a given set of chemical constituents the &lt;span&gt;XtalOpt&lt;/span&gt; algorithm can search for (meta)stable crystal structures with fixed or varying compositions and optionally with specific functionalities – a grand challenge in computational materials science, chemistry and physics.&lt;/div&gt;&lt;div&gt;&lt;em&gt;Solution method:&lt;/em&gt; During the search process, the convex hull of the chemical system is calculated and updated. Instead of enthalpy, the “distance above the convex hull” is used as the target value for global optimization. The genetic operations are revised to enable the evolution of parent structures with different compositions, and to possibly produce new compositions. To further enhance the code’s capability of performing a multi-objective search, the Pareto optimization scheme is implemented. This allows the user to choose from","PeriodicalId":285,"journal":{"name":"Computer Physics Communications","volume":"320 ","pages":"Article 109910"},"PeriodicalIF":3.4,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145733047","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}

{"title":"Quantum transport with spin-orbit coupling: New developments in TranSIESTA","authors":"Nils Wittemeier ,&nbsp;Nick Papior ,&nbsp;Mads Brandbyge ,&nbsp;Zeila Zanolli ,&nbsp;Pablo Ordejon","doi":"10.1016/j.cpc.2025.109996","DOIUrl":"10.1016/j.cpc.2025.109996","url":null,"abstract":"<div><div>We present the implementation of spinor quantum transport within the non-equilibrium Green’s function (NEGF) code TranSIESTA based on Density Functional Theory (DFT). First-principles methods play an essential role in molecular and material modelling, and the DFT+NEGF approach has become a widely-used tool for quantum transport simulation. Existing (open-source) DFT-based quantum transport codes either model non-equilibrium/finite-bias cases in an approximate way or rely on the collinear spin approximation. Our new implementation closes this gap and enables the TranSIESTA code to use full spinor-wave functions. Thereby it provides a method for transport simulation of topological materials and devices based on spin-orbit coupling (SOC) or non-collinear spins. These materials hold enormous potential for the development of ultra-low-energy electronics urgently needed for the design of sustainable technology. The new feature is tested on relevant systems determining magnetoresistance in iron nanostructures and transport properties of a lateral transition metal dichalcogenide heterojunction.</div></div>","PeriodicalId":285,"journal":{"name":"Computer Physics Communications","volume":"320 ","pages":"Article 109996"},"PeriodicalIF":3.4,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145836436","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}

{"title":"Verification of a hybrid kinetic-gyrokinetic model using the advanced semi-Lagrange code ssV","authors":"Sreenivasa chary Thatikonda ,&nbsp;F.N. De Oliveira-Lopes ,&nbsp;A. Mustonen ,&nbsp;K. Pommois ,&nbsp;D. Told ,&nbsp;F. Jenko","doi":"10.1016/j.cpc.2025.109980","DOIUrl":"10.1016/j.cpc.2025.109980","url":null,"abstract":"<div><div>The super simple Vlasov (ssV) code was developed to study instabilities, turbulence, and reconnection in weakly magnetized plasmas, such as the solar wind in the dissipation range and the edge of fusion plasmas. The ssV code overcomes the limitations of standard gyrokinetic theory by using a hybrid kinetic-gyrokinetic model that incorporates fully kinetic ions and gyrokinetic electrons. This hybrid kinetic-gyrokinetic model enables accurate modeling in regimes characterized by steep gradients and high-frequency dynamics. To achieve this, ssV implements a set of semi-Lagrangian numerical schemes, including Positive Flux Conservative (PFC), Flux Conservative fifth-order (FCV), FCV with Umeda limiters, and a Semi-Lagrangian Monotonicity-Preserving fifth-order scheme (SLMP5). Benchmark problems such as Landau damping, ion-acoustic waves, ion Bernstein waves, and kinetic Alfvén waves were employed to evaluate the schemes. The SLMP5 scheme consistently delivered the best overall accuracy and numerical stability performance. The code also addresses well-known electromagnetic gyrokinetic simulation issues, such as the Ampère cancellation problem, using carefully chosen velocity-space resolutions and accurate integral evaluation.</div></div>","PeriodicalId":285,"journal":{"name":"Computer Physics Communications","volume":"320 ","pages":"Article 109980"},"PeriodicalIF":3.4,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145786467","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}

{"title":"Semi-implicit scheme for multi-species collision operators in Tokamak Plasma Simulations","authors":"Dandan Liao ,&nbsp;Lei Ye ,&nbsp;Pengfei Zhao ,&nbsp;Qilong Ren ,&nbsp;Nong Xiang","doi":"10.1016/j.cpc.2025.110012","DOIUrl":"10.1016/j.cpc.2025.110012","url":null,"abstract":"<div><div>A second-order semi-implicit time integration method has been developed for solving the linearized collision operator in multi-species plasmas. A key feature of this method is that it treats the collision operator as a single entity, avoiding the operator splitting between its test particle and field particle components. This scheme employs an implicit trapezoidal time integration scheme for the isothermal test particle part (including pitch-angle scattering and energy diffusion) with a finite volume discretization in (<em>v</em>_∥, <em>μ</em>) velocity coordinates, while the non-isothermal model term and field particle part are treated explicitly. This approach avoids the species cross-coupling required by fully implicit schemes, enabling the collision term to be computed efficiently with a banded/sparse-matrix solver. The method has been implemented in the gyrokinetic semi-Lagrangian code NLT and verified through multi-species relaxation tests and neoclassical transport simulations. Numerical benchmarks against explicit methods confirm its robustness, achieving order-of-magnitude improvements in the allowable time-step size, particularly in simulations of electron-ion collisions. Furthermore, the numerical discretization rigorously preserves particle number, momentum, and energy conservation, maintains the self-adjoint property of the collision operator, and satisfies Boltzmann’s H-theorem.</div></div>","PeriodicalId":285,"journal":{"name":"Computer Physics Communications","volume":"320 ","pages":"Article 110012"},"PeriodicalIF":3.4,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145880486","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}