# The QB program: Analysing resonances using R-matrix theory

## Description

Abstract A procedure for analysing resonances in atomic and molecular collision theory is programmed, which exploits the analytic properties of R-matrix theory to obtain the energy derivative of the reactance (K) matrix. This procedure is based on the QB method (J. Phys. B 29 (1996) 4529) which defines matrices Q and B in terms of asymptotic solutions, the R-matrix and energy derivatives, such that dK/dE = B^(-1)Q, from which eigenphase gradients of the K matrix can be obtained. Resonance positions ... Title of program: QB Catalogue Id: ADJC_v1_0 Nature of problem A procedure for analysing resonances in atomic and molecular collision theory is programmed, which exploits the analytic properties of R-matrix theory to obtain the energy derivative of the reactance (K) matrix and hence the eigenphase sum derivative. Searching for maxima in this gives positions, widths and identifications for all resonances in a given energy range. Versions of this program held in the CPC repository in Mendeley Data ADJC_v1_0; QB; 10.1016/S0010-4655(98)00059-9 This program has been imported from the CPC Program Library held at Queen's University Belfast (1969-2018)