Determine whether the TDQMC energy bounds the exact ground-state energy

Determine whether the energy produced by the time-dependent quantum Monte Carlo (TDQMC) method provides a bound on the exact ground-state energy.

Background

The paper derives a conditional interaction for TDQMC using Bayesian conditioning and the Nadaraya–Watson estimator, and applies the resulting framework to fermionic and spinor dynamics. The energy estimator is evaluated with the bare electron–electron interaction, while the conditional potential is used only in the equations of motion.

Although the nonlocality length is selected by minimizing the TDQMC energy, the paper explicitly distinguishes this self-consistency criterion from a variational principle: the resulting energy is not established as an upper bound. The authors identify as an unresolved issue whether the method’s energy bounds the exact ground-state energy.