# RELCI: A program for relativistic configuration interaction calculations ☆

## Description

Abstract The set-up and diagonalization of (large) Hamiltonian matrices are two key elements in studying the structure and properties of many-electron atoms and ions. The efficiency in dealing with these tasks eventually determines for which atomic systems useful ab initio predictions can be made today and how accurate these predictions are. To facilitate further structure calculations, in particular for open-shell atoms and ions, here we present a new configuration interaction program in the framewor... Title of program: RELCI Catalogue Id: ADQH_v1_0 Nature of problem Approximate atomic wave functions are determined by diagonalizing the Hamiltonian matrix within an appropriate many-particle basis. Here, the construction of the configuration interaction (CI) basis follows the same principles as in the structure code GRASP92 [1] which is utilized to generate the configuration state functions (CSF) and the radial orbitals for all subshells of the given active space. Versions of this program held in the CPC repository in Mendeley Data ADQH_v1_0; RELCI; 10.1016/S0010-4655(02)00463-0 This program has been imported from the CPC Program Library held at Queen's University Belfast (1969-2019)