Schur complement solver for Quantum Monte-Carlo simulations of strongly interacting fermions
This work provides a faster solver for strongly interacting fermion simulations, which is a computational bottleneck in condensed matter physics.
The authors present a non-iterative Schur complement solver for sparse linear systems in Quantum Monte-Carlo simulations of strongly interacting fermions. The solver is faster than iterative methods like Conjugate Gradient for strong interactions, achieving significant speed-ups, especially for multiple right-hand sides, with benchmarks on graphene lattice models.
We present a non-iterative solver based on the Schur complement method for sparse linear systems of special form which appear in Quantum Monte-Carlo (QMC) simulations of strongly interacting fermions on the lattice. While the number of floating-point operations for this solver scales as the cube of the number of lattice sites, for practically relevant lattice sizes it is still significantly faster than iterative solvers such as the Conjugate Gradient method in the regime of strong inter-fermion interactions, for example, in the vicinity of quantum phase transitions. The speed-up is even more dramatic for the solution of multiple linear systems with different right-hand sides. We present benchmark results for QMC simulations of the tight-binding models on the hexagonal graphene lattice with on-site (Hubbard) and non-local (Coulomb) interactions, and demonstrate the potential for further speed-up using GPU.