text: 266,40,1364217858641829888,1140025148004810752,Pierre Arthuis,"🗞 New paper alert! 🗞 We propose a new many-body expansion formalism for open-shell mid-mass nuclei. Additional perk: it comes with contributions derived at all orders! <LINK> <LINK> In-Medium Similarity Renormalization Group has been a theory of choice for ab initio many-body practitioners, and with its Multi-Reference and Valence-Space counterparts have been instrumental in recent progress. Figure from H.Hergert, Front. Phys. 8:379, <LINK> <LINK> Though MR-IMSRG and VS-IMSRG are already able to tackle open-shell nuclei, they are pretty costly methods. Here we propose a single-reference, symmetry-breaking alternative, similar to the recently successful Bogoliubov MBPT. Figure from Tichai et al., <LINK> <LINK> Because Bogoliubov IMSRG inherently relies on a simple commutator, the structure of its contributions is pretty well constrained. This makes for an easy automated generation of diagrams and expressions from the get go. Figure taken from our new paper, <LINK> <LINK> So with this new paper, we have updated the Automated Diagram Generator ADG to v3.0.0. It is now able to generate BIMSRG expressions at arbitrary orders and for traditional or exotic truncations. <LINK>",https://arxiv.org/abs/2102.10889,"The goal of the present paper is twofold. First, a novel expansion many-body method applicable to superfluid open-shell nuclei, the so-called Bogoliubov in-medium similarity renormalization group (BIMSRG) theory, is formulated. This generalization of standard single-reference IMSRG theory for closed-shell systems parallels the recent extensions of coupled cluster, self-consistent Green's function or many-body perturbation theory. Within the realm of IMSRG theories, BIMSRG provides an interesting alternative to the already existing multi-reference IMSRG (MR-IMSRG) method applicable to open-shell nuclei. The algebraic equations for low-order approximations, i.e., BIMSRG(1) and BIMSRG(2), can be derived manually without much difficulty. However, such a methodology becomes already impractical and error prone for the derivation of the BIMSRG(3) equations, which are eventually needed to reach high accuracy. Based on a diagrammatic formulation of BIMSRG theory, the second objective of the present paper is thus to describe the third version (v3.0.0) of the ADG code that automatically (1) generates all valid BIMSRG(n) diagrams and (2) evaluates their algebraic expressions in a matter of seconds. This is achieved in such a way that equations can easily be retrieved for both the flow equation and the Magnus expansion formulations of BIMSRG. Expanding on this work, the first future objective is to numerically implement BIMSRG(2) (eventually BIMSRG(3)) equations and perform ab initio calculations of mid-mass open-shell nuclei. ","ADG: Automated generation and evaluation of many-body diagrams III.