COLOSS: Complex-scaled Optical and couLOmb Scattering Solver

TL;DR

COLOSS is a new computational tool that uses complex scaling to accurately solve Coulomb scattering problems, providing reliable S-matrix and cross-section calculations with flexible potential handling.

Contribution

It introduces a bound-state technique based on complex scaling for scattering, with implementation of realistic optical potentials and adaptable rotation methods for enhanced accuracy.

Findings

High accuracy compared to direct integration methods

Effective handling of long-range Coulomb interactions

Flexible potential parameter input

Abstract

We introduce COLOSS, a program designed to address the scattering problem using a bound-state technique known as complex scaling. In this method, the oscillatory boundary conditions of the wave function are transformed into exponentially decaying ones, accommodating the long-range Coulomb interaction. The program implements the Woods-Saxon form of a realistic optical potential, with all potential parameters included in a well-designed input format for ease of use. This design offers users straightforward access to compute \(S\)-matrices and cross-sections of the scattering process. We provide thorough discussions on the precision of Lagrange functions and their benefits in evaluating matrix elements. Additionally, COLOSS incorporates two distinct rotation methods, making it adaptable to potentials without analytical expressions. Comparative results demonstrate that COLOSS achieves high accuracy when compared with the direct integration method, Numerov, underscoring its utility and effectiveness in scattering calculations.