Multigrid solver for clover fermions

TL;DR

This paper introduces an adaptive multigrid solver for Wilson clover fermions that significantly accelerates solutions of the Dirac equation in lattice QCD, maintaining accuracy and efficiency across different quark masses.

Contribution

The paper develops a novel multigrid Dirac solver with even-odd preconditioning and mixed precision, achieving order-of-magnitude speedups over traditional Krylov methods.

Findings

Order-of-magnitude reduction in solution time

Effective for decreasing quark masses

Comparable accuracy to double precision

Abstract

We present an adaptive multigrid Dirac solver developed for Wilson clover fermions which offers order-of-magnitude reductions in solution time compared to conventional Krylov solvers. The solver incorporates even-odd preconditioning and mixed precision to solve the Dirac equation to double precision accuracy and shows only a mild increase in time to solution for decreasing quark mass. We show actual time to solution on production lattices in comparison to conventional Krylov solvers and will also discuss the setup process and its relative cost to the total solution time.