Structural and dynamical properties of superfluid helium: a density functional approach

TL;DR

This paper introduces a new density functional for liquid helium-4 that accurately models its static and dynamic properties, including surface phenomena and elementary excitations, aligning well with ab initio results.

Contribution

A novel density functional that captures static response and phonon-roton dispersion, enabling detailed study of superfluid helium's structural and dynamical properties.

Findings

Predictions closely match ab initio Monte Carlo results.

Successfully models surface, droplet, and film properties at zero temperature.

Analyzes elementary excitation spectra of free surfaces and films.

Abstract

We present a novel density functional for liquid 4He, properly accounting for the static response function and the phonon-roton dispersion in the uniform liquid. The functional is used to study both structural and dynamical properties of superfluid helium in various geometries. The equilibrium properties of the free surface, droplets and films at zero temperature are calculated. Our predictions agree closely to the results of ab initio Monte Carlo calculations, when available. The introduction of a phenomenological velocity dependent interaction, which accounts for backflow effects, is discussed. The spectrum of the elementary excitations of the free surface and films is studied.