Domain decomposition efforts in Chroma

Abstract

Multilevel integration is a technique used in lattice quantum chromodynamics (LQCD) simulations, where the correlation functions are decomposed into factors that depend only on fields localized within specific lattice subdomains. The approach significantly improves the efficiency of the calculations because the factors can be independently integrated. The main challenge in implementing multilevel integration is that the standard formulation of the LQCD action is not local in the presence of fermions. However, past studies have shown that approximations of the quark propagator and the fermionic determinant, which depend on the gauge fields within specific subdomains, can still be effective. We will present the current progress in supporting domain decomposition within the Chroma software, which is necessary for implementing multilevel integration approaches. Most of the efforts have focused on extending the Chroma code base to efficiently manipulate subdomains for lattice fields and operators, as well as performing inversions and eigendecompositions within these domains.