RHODIUM: A post-processor for BIGSTICK configuration-interaction wave functions
Calvin W. Johnson
TL;DR
RHODIUM addresses a key limitation of BIGSTICK by providing post-processing capabilities that connect wave functions across bases with different quantum numbers to compute density matrices, spectroscopic amplitudes, and related one-body observables. It reads .bas and .wfn files produced by BIGSTICK, applies a range of one-body operations, and outputs results in BIGSTICK-compatible formats (.wfn, .dres, .spres), without Hamiltonian diagonalization or two-body operator handling. The approach leverages angular-momentum coupling and, when needed, uses the J_+ raising operator to recover missing density elements and to access cross-parity or proton-neutron densities. This toolkit broadens the observable scope in nuclear structure studies and supports workflows such as cross-basis projections, beta-decay type densities, and spectroscopic-factor analysis, all under an MIT license with OpenMP parallelization implemented.
Abstract
RHODIUM is a postprocessing code for nuclear structure physics. It can be used to compute density matrices, spectroscopic amplitudes, and other information, from wave function and basis files created by the configuration-interaction shell-model code BIGSTICK. The source code is available at github.com/cwjsdsu/Rhodium. This manual gives detailed instructions how to use.