AFQMC
Auxiliary-field Quantum Monte Carlo (AFQMC) is a stochastic method for solving the non-relativistic quantum many-body problem, with particular use in electronic structure calculations for atoms, molecules, and solids. It projects the ground state by imaginary-time propagation using the operator exp(-tau H), where H is the many-body Hamiltonian.
The central idea is to decouple the two-body interaction via a Hubbard-Stratonovich transformation, introducing auxiliary fields
A major challenge is the fermion sign (or phase) problem. AFQMC mitigates this with approximations such as
Variants include finite-temperature AFQMC and the phaseless AFQMC algorithm. The method relies on choices of trial
Applications span electronic structure calculations for molecules and solids, including challenging transition-metal complexes and strongly correlated