Engineering topics

Calcavecchia, Francesco

Publications and source records attributed to Calcavecchia, Francesco.

2 records

DOE OSTI2023

Static Self-Energy and Effective Mass of the Homogeneous Electron Gas from Quantum Monte Carlo Calculations

We discuss the methodology of quantum Monte Carlo calculations of the effective mass based on the static self-energy Σ(k,0). We then use variational Monte Carlo calculations of Σ(k,0) of the homogeneous electron gas at various densities to obtain results very close to perturbative G 0 W 0 calculations for values of the density parameter 1 ≤ r s ≤ 10. Here, the obtained values for the effective mass are close to diagrammatic Monte Carlo results and disagree with previous quantum Monte Carlo calculations based on a heuristic mapping of excitation energies to those of an ideal gas.

36 MATERIALS SCIENCE↗

DOE OSTI2014

Sign problem of the fermionic shadow wave function

Here, we present a whole series of methods to alleviate the sign problem of the fermionic shadow wave function in the context of variational Monte Carlo. The effectiveness of our techniques is demonstrated on liquid 3 He. We found that although the variance is reduced, the gain in efficiency is restricted by the increased computational cost. Yet, this development not only extends the scope of the fermionic shadow wave function, but also facilitates highly accurate quantum Monte Carlo simulations previously thought not feasible.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗