RAD-TRAP, a program for the computation of the eigenvalues and eigenfunctions of the Holstein radiation-trapping equation

Abstract
Radiation trapping is described by the Holstein equation, a Fredholm integral equation of the second kind. By combining analytical and numerical techniques, the presented code efficiently computes the eigenvalues and eigenfunctions of this equation for three important geometries: plane-parallel slab, long cylinder, and spherically symmetric geometry; all practically occuring spectral lineshapes are considered. The program is written in standard Fortran.

Title of program: RAD-TRAP
Catalogue Id: ACLB_v1_0

Nature of problem
Computation of the eigenvalues and eigenfunctions of the Holstein integral equation describing radiation trapping in an atomic vapor (in one-dimensional geometries).

Versions of this program held in the CPC repository in Mendeley Data
ACLB_v2_0; RAD-TRAP 2; 10.1016/0010-4655(93)90009-2
ACLB_v1_0; RAD-TRAP; 10.1016/0010-4655(93)90108-O

This program has been imported from the CPC Program Library held at Queen's University Belfast (1969-2019)

**摘要** 辐射俘获可通过霍尔斯坦方程（Holstein equation）描述，该方程属于第二类弗雷德霍姆积分方程。本代码结合解析与数值技术，可高效求解三类重要几何构型下该方程的本征值与本征函数：平行平面板、长圆柱与球对称几何；且覆盖了所有实际存在的谱线线型。本程序采用标准Fortran语言编写。
程序名称：RAD-TRAP
目录编号：ACLB_v1_0

**问题属性** 本程序用于求解描述原子蒸气中辐射俘获的霍尔斯坦积分方程的本征值与本征函数（适配一维几何构型）。

曼德莱数据集（Mendeley Data）中CPC库收录的该程序版本：
ACLB_v2_0; RAD-TRAP 2; 10.1016/0010-4655(93)90009-2
ACLB_v1_0; RAD-TRAP; 10.1016/0010-4655(93)90108-O

本程序源自贝尔法斯特女王大学所维护的CPC程序库（1969-2019）