Exact finite-flow error structure in IMSRG calculations

Determine the number and exact functional form of the coefficient functions governing finite-flow errors in in-medium similarity renormalization group calculations.

Background

The IMSRG emulator models finite-flow errors as sums of exponentially decaying terms whose amplitudes and decay rates depend on the Hamiltonian parameters. This representation motivates the corresponding data-driven components of the PMM–IMSRG emulator.

However, the underlying IMSRG calculation does not provide the number or exact forms of these terms analytically, so the emulator must learn universal approximations for them from data.