Boson Slave Solver (BoSS) v1.1

Abstract: Accurate and computationally efficient modeling of systems of interacting electrons is an outstanding problem in theoretical and computational materials science. For materials where strong electronic interactions are primarily of a localized character and act within a subspace of localized quantum states on separate atomic sites (e.g., in transition metal and rare-earth compounds), their electronic behaviors are typically described by the Hubbard model and its extensions. In this work, we describe BoSS (Boson Slave Solver), a software implementation of the slave-boson method appropriate for describing a variety of extended Hubbard models, namely $p-d$ models that include both the interacting atomic sites ("$d$" states) and non-interacting or ligand sites ("$p$" states). We provide a theoretical background, a description of the equations solved by BoSS, an overview of the algorithms used, the key input/output and control variables of the software program, and tutorial examples of its use featuring band renormalization in SrVO$_3$, Ni $3d$ multiplet structure in LaNiO$_3$, and the relation between the formation of magnetic moments and insulating behavior in SmNiO$_3$. BoSS interfaces directly with popular electronic structure codes: it can read the output of the Wannier90 software package which postprocesses results from workhorse electronic structure software such as Quantum Espresso or VASP.