ELSEPA–Dirac partial-wave calculation of elastic scattering of electrons and positrons by atoms, positive ions and molecules (New Version Announcement)

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 Fernández-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. The previous version of this program (ADUS_v1_0) may be found at https://dx.doi.org/10.1016/j.cpc.2004.09.006.

本文介绍了Fortran程序ELSEPA的新版本，该程序可计算电子与正电子弹性散射的微分截面及积分截面。关于程序及其应用的详细信息，请参见原始论文[Comput. Phys. Commun. 165 (2005) 157–190]。狄拉克相移（Dirac phase shifts）现通过最新发布的子程序包RADIAL（Salvat与Fernández-Varea，2019）计算，该子程序包采用稳健且精确的幂级数方法求解实或复中心势下的径向波方程。此外，元素固体中原子的弹性碰撞通过Bote等人（2009）提出的muffin-tin光学模型势描述，该势函数较原始ELSEPA代码中的模型更为精细灵活，且可通过调整吸收势使非弹性截面与实验数据高度吻合。借助RADIAL子程序，ELSEPA的核心工作简化为两点：（1）相互作用势的定义；（2）散射振幅分波级数的求和。新版本代码的结构已优化简化，并采用了更严格的分波级数收敛判定准则。程序分发包中包含GNUPLOT脚本，可便捷实现计算结果的可视化。本程序的旧版本（ADUS_v1_0）可通过以下链接获取：https://dx.doi.org/10.1016/j.cpc.2004.09.006。