Analytic continuation average spectrum method for quantum liquids

TL;DR

This paper applies the average spectrum method to quantum liquids, successfully revealing detailed dynamic structure factors from quantum Monte Carlo data, outperforming traditional maximum entropy methods, and marks its first use in realistic off-lattice systems.

Contribution

The paper demonstrates the effectiveness of the ASM in analyzing quantum liquids and provides the first application of ASM to realistic off-lattice systems.

Findings

ASM reveals resolved modes in quantum liquids

ASM outperforms maximum entropy in detail resolution

First application of ASM in off-lattice systems

Abstract

We revisit the problem of determining the real-frequency density response in quantum fluids via analytical continuation of imaginary-time quantum Monte Carlo data. We demonstrate that the average spectrum method (ASM) is capable of revealing resolved modes in the dynamic structure factor of both ortho-deuterium and liquid para-hydrogen, in agreement with experiments and quantum mode-coupling theories, while the maximum entropy approach yields only a smooth unimodal spectrum. Outstanding issues are discussed. Our work provides the first application of the ASM method in realistic off-lattice systems.