Opty : a universal optical model code for the elastic scattering of spinless particles

Abstract

1. General description of the programme : The computer programme OPTY calculates the predictions of the Optical Model for the elastic scattering of spinless particles.Three types of parametrization (see below) are available for the real and the imaginary parts of the optical model potential (OMP). For a given option of the OMP the program automatically searches the optimum values of the potential parameters by minimizing the x$^{2}$-value $x^{2}(a_{1},..a_{N}) = \sum_{i} \Big[\frac{^{\sigma}exp (^{\theta}i) - \sigma_{th} (\theta_{i}, a_{1}, ...a_{N})}{\Delta \sigma_{exp} (\theta_{i})}\Big]^{2}$ (1) according to the GRADIENT$^{1)}$ and/or the SIMPLEX$^{2,3)}$ methods. At each angle $\theta_{i}$ the quantities $\sigma_{exp} (\theta_{i}), \Delta \sigma_{exp}(\theta_{i})$ and $\sigma_{th}(\theta_{i})$ represent the experimental value, the estimated error and the theoretical value of the elastic scattering differential cross section, respectively. The OMP parameters are denoted by $a_{1}, ... ,a_{N}$. The program allows four main options for the OMP: A. Generalized$^{4)}$ Woods-Saxon (GWS): $v_{opt}(r) = U*[f(r,r_{U},a_{U})]^{WYR} + i*W_{v}*[f(r,r_{v},a_{v})]^{WYI} - i*(4a_{S}W_{S}) * \frac{d}{dr}[f(r,r_{S},a_{S})]^{WYI}\equiv (WS)**WYR+i ((WS)**WYI + WSD)$ (2) where $f(r,r_{x},a_{x}) = [l+exp(\frac{r-r_{x}*A^{1/3}}{a_{x}})]^{-1}$ (3) The program optimizes the values of the parameters according to the search-configuration (see card-set VI of input data) [...