Importance-sampling diagonalization algorithm for large-scale shell model calculations onN=80isotones

Abstract

An iterative matrix diagonalization algorithm endowed with an importance sampling, recently reformulated and tested through large-scale shell model calculations on some heavy Xe isotopes, is here applied to $N=80$ isotones. For these nuclei, the iterative sampling procedure is shown to converge more rapidly than in the case of Xe isotopes. The improved convergence rate enables us to produce accurate eigenvalues and eigenfunctions even in spaces of dimensions $N\ensuremath{\sim}{10}^{9}$. It is therefore possible to offer an exhaustive description of low-energy spectroscopic properties for all $N=80$ isotones from ${}^{132}$Te up to ${}^{140}$Nd through the calculation of spectra and transition strengths. The results are fairly consistent with the available experimental data and with other shell model calculations based on the Lanczos algorithm.