ADG: automated generation and evaluation of many-body diagrams

Abstract The goal of the present paper is twofold. First, a novel expansion many-body method applicable to superfluid open-shell nuclei, so-called Bogoliubov in-medium similarity renormalization group (BIMSRG) theory, formulated. This generalization standard single-reference IMSRG theory for closed-shell systems parallels recent extensions coupled cluster, self-consistent Green’s function or perturbation theory. Within realm theories, BIMSRG provides an interesting alternative already existing multi-reference (MR-IMSRG) nuclei. algebraic equations low-order approximations, i.e., BIMSRG(1) and BIMSRG(2), can be derived manually without much difficulty. However, such methodology becomes impractical error prone derivation BIMSRG(3) equations, which are eventually needed reach high accuracy. Based on diagrammatic formulation second objective thus describe third version (v3.0) code that automatically (1) generates all valid BIMSRG(n) diagrams (2) evaluates their expressions in matter seconds. achieved way easily retrieved both flow equation Magnus formulations BIMSRG. Expanding this work, first future numerically implement BIMSRG(2) (eventually BIMSRG(3)) perform ab initio calculations mid-mass