Abstract A new version of the Fortran program elsepa , which calculates differential and integrated cross sections for elastic scattering of electrons and positrons, is presented. Details of the program and its applications are given in the original paper [Comput. Phys. Commun. 165 (2005) 157–190]. Dirac phase shifts are now calculated by using the recently published subroutine package radial (Salvat and Fernandez-Varea, 2019), which solves the radial wave equation for real or complex central potentials by means of a robust and accurate power-series method. In addition, elastic collisions with atoms in elemental solids are described by using the muffin-tin optical model potential proposed by Bote et al., (2009), which is somewhat more elaborate and flexible than that in the original elsepa code and allows adjusting the absorption potential to give inelastic cross sections in close agreement with empirical data. With the use of the radial subroutines, the work of elsepa is reduced to (1) the definition of the interaction potential and (2) the summation of the partial-wave series of the scattering amplitudes. The structure of the new code has been simplified and stricter criteria for the convergence of the partial-wave series have been adopted. The distribution package includes gnuplot scripts for easy visualization of the calculation results. Program summary Program Title: elsepa CPC Library link to program files: http://dx.doi.org/10.17632/w4hm5vymym.1 Licensing provisions: CC BY NC 3.0 Programming language: Fortran 90 Journal reference of previous version: Comput. Phys. Commun. 165 (2005) 157–190 Does the new version supersede the previous version?: Yes Reasons for the new version: This new version offers increased accuracy, and a more flexible modeling of elastic collisions of electrons and positrons with atoms in elemental solids. Summary of revisions: The calculation of phase shifts is now performed by the generic subroutines of the radial package [1]. A more flexible optical-model potential for scattering in solids is included [2]. Stricter criteria for convergence of the partial-wave series are applied. The distribution package has been reorganized, with the numerical database files now placed in a separate directory; scripts for direct visualization of the calculation results with the plotting program gnuplot ( http://www.gnuplot.info ) are also included. Nature of problem: The code calculates differential cross sections, total cross sections and transport cross sections for single elastic scattering of electrons and positrons by neutral atoms, positive ions and randomly oriented molecules. When the energy of the projectile is less than about 5 MeV, the programs also compute scattering amplitudes and spin polarization functions. Solution method: The effective interaction between the projectile and the target atom is represented by a local central potential that can optionally include an imaginary (absorptive) part to account approximately for the coupling with inelastic channels. For projectiles with kinetic energy less that about 5 MeV, the code performs a conventional relativistic Dirac partial-wave analysis. For higher kinetic energies, where the convergence of the partial-wave series is too slow, approximate factorization methods are used. The programs only admit kinetic energies higher than 5 eV, a practical lower limit that may be changed by editing the source files. Additional comments including restrictions and unusual features: The calculations are based on the static-field approximation. The optional correlation-polarization and inelastic absorption corrections are obtained from approximate, semi-empirical models. elsepa allows considering an absorption potential only for projectiles with energies less than about 1 MeV; for higher energies, the absorption potential is set to zero to prevent the occurrence of numerical instabilities. Calculations for molecules are based on a single-scattering independent-atom approximation. To ensure accuracy of the results for scattering by ions, the electron density of the ion must be supplied by the user; it can be generated, e.g., by running the program dhfs of the radial package [1]. Acknowledgments We are indebted to Dr John Villarrubia for pointing out various cases of incomplete convergence of the original code. Financial support from the Spanish Ministerio de Ciencia, Innovacion y Universidades / Agencia Estatal de Investigacion, Spain / European Regional Development Fund , European Union, (project no. RTI2018-098117-B-C22) is gratefully aknowledged. References: [1] F. Salvat, J.M. Fernandez-Varea, Comput. Phys. Commun. 240 (2019) 165–177. [2] D. Bote, F. Salvat, A. Jablonski, C.J. Powell, J. Electron. Spectrosc. Rel. Phenom. 175 (2009) 41—54.

中文翻译：

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elsepa–Dirac 分波计算原子、正离子和分子对电子和正电子的弹性散射（新版本公告）

摘要 介绍了 Fortran 程序 elsepa 的新版本，该程序可计算电子和正电子弹性散射的微分和积分截面。该程序及其应用的详细信息在原始论文 [Comput. 物理。社区。165 (2005) 157–190]。Dirac 相移现在使用最近发布的子程序包 Radial（Salvat 和 Fernandez-Varea，2019 年）计算，该程序包通过稳健且准确的幂级数方法求解实数或复数中心势的径向波动方程。此外，使用 Bote 等人 (2009) 提出的 muffin-tin 光学模型势描述了与元素固体中原子的弹性碰撞，这比原来的 elsepa 代码更加复杂和灵活，并且允许调整吸收潜力以提供与经验数据非常一致的非弹性横截面。通过使用径向子程序，elsepa 的工作被简化为（1）相互作用势的定义和（2）散射幅度的部分波级数的总和。新代码的结构得到了简化，并采用了更严格的分波级数收敛标准。分发包包含 gnuplot 脚本，可轻松实现计算结果的可视化。程序概要 程序名称：elsepa CPC 库程序文件链接：http://dx.doi.org/10.17632/w4hm5vymym.1 许可条款：CC BY NC 3.0 编程语言：Fortran 90 以前版本的期刊参考：Comput。物理。社区。165 (2005) 157–190 新版本是否取代了以前的版本？：是 新版本的原因：这个新版本提供了更高的准确性，以及更灵活的电子和正电子与元素固体中原子的弹性碰撞建模。修订摘要：相移的计算现在由径向包 [1] 的通用子程序执行。包括一个更灵活的固体散射光学模型潜力 [2]。应用更严格的分波级数收敛标准。分发包已经过重新组织，数字数据库文件现在放在一个单独的目录中；使用绘图程序 gnuplot ( http://www.gnuplot.txt ) 直接可视化计算结果的脚本。info ) 也包括在内。问题性质：代码计算中性原子、正离子和随机取向分子对电子和正电子的单次弹性散射的微分截面、总截面和传输截面。当射弹的能量小于约 5 MeV 时，程序还会计算散射幅度和自旋极化函数。求解方法：射弹和目标原子之间的有效相互作用由局部中心势表示，该中心势可以可选地包括虚（吸收）部分，以近似解释与非弹性通道的耦合。对于动能小于 5 MeV 的射弹，代码执行传统的相对论狄拉克分波分析。对于更高的动能，在分波级数收敛太慢的情况下，使用近似分解方法。程序只允许高于 5 eV 的动能，这是一个实际的下限，可以通过编辑源文件来改变。包括限制和异常特征在内的附加说明：计算基于静态场近似。可选的相关极化和非弹性吸收校正是从近似的半经验模型中获得的。elsepa 允许仅考虑能量小于约 1 MeV 的射弹的吸收潜力；对于更高的能量，吸收电位设置为零以防止出现数值不稳定性。分子的计算基于单散射独立原子近似。为保证离子散射结果的准确性，离子的电子密度必须由用户提供；例如，它可以通过运行径向包 [1] 的程序 dhfs 来生成。致谢 我们感谢 John Villarrubia 博士指出原始代码不完全收敛的各种情况。非常感谢西班牙教育部长、创新和大学/Agencia Estatal de Investigacion、西班牙/欧洲区域发展基金、欧盟（项目编号 RTI2018-098117-B-C22）的财政支持。参考文献： [1] F. Salvat, JM Fernandez-Varea, Comput. 物理。社区。240 (2019) 165-177。[2] D. Bote、F. Salvat、A. Jablonski、CJ Powell、J. Electron。光谱c。相对。现象。175 (2009) 41—54。例如，它可以通过运行径向包 [1] 的程序 dhfs 来生成。致谢 我们感谢 John Villarrubia 博士指出原始代码不完全收敛的各种情况。非常感谢西班牙教育部长、创新和大学/Agencia Estatal de Investigacion、西班牙/欧洲区域发展基金、欧盟（项目编号 RTI2018-098117-B-C22）的财政支持。参考文献： [1] F. Salvat, JM Fernandez-Varea, Comput. 物理。社区。240 (2019) 165-177。[2] D. Bote、F. Salvat、A. Jablonski、CJ Powell、J. Electron。光谱c。相对。现象。175 (2009) 41—54。例如，它可以通过运行径向包 [1] 的程序 dhfs 来生成。致谢 我们感谢 John Villarrubia 博士指出原始代码不完全收敛的各种情况。非常感谢西班牙教育部长、创新和大学/Agencia Estatal de Investigacion、西班牙/欧洲区域发展基金、欧盟（项目编号 RTI2018-098117-B-C22）的财政支持。参考文献： [1] F. Salvat, JM Fernandez-Varea, Comput. 物理。社区。240 (2019) 165-177。[2] D. Bote、F. Salvat、A. Jablonski、CJ Powell、J. Electron。光谱c。相对。现象。175 (2009) 41—54。非常感谢西班牙教育部长、创新和大学/Agencia Estatal de Investigacion、西班牙/欧洲区域发展基金、欧盟（项目编号 RTI2018-098117-B-C22）的财政支持。参考文献： [1] F. Salvat, JM Fernandez-Varea, Comput. 物理。社区。240 (2019) 165-177。[2] D. Bote、F. Salvat、A. Jablonski、CJ Powell、J. Electron。光谱c。相对。现象。175 (2009) 41—54。非常感谢西班牙教育部长、创新和大学/Agencia Estatal de Investigacion、西班牙/欧洲区域发展基金、欧盟（项目编号 RTI2018-098117-B-C22）的财政支持。参考文献： [1] F. Salvat, JM Fernandez-Varea, Comput. 物理。社区。240 (2019) 165-177。[2] D. Bote、F. Salvat、A. Jablonski、CJ Powell、J. Electron。光谱c。相对。现象。175 (2009) 41—54。现象。175 (2009) 41—54。现象。175 (2009) 41—54。