A coordinated wavefunction for the ground state of liquid helium-4

TL;DR

This paper introduces a new variational wavefunction ansatz for liquid helium-4 that captures correlations more effectively, enabling better modeling of inhomogeneous systems and surface phenomena without explicit surface terms.

Contribution

The authors develop a novel coordinated wavefunction ansatz that improves the description of correlations in liquid helium-4 and naturally models inhomogeneous states and surfaces.

Findings

Accurately describes mid-range correlations in liquid helium-4

Enables study of inhomogeneous systems and surfaces

Does not require explicit surface terms in the wavefunction

Abstract

We present a variational ansatz for the ground state of a strongly correlated Bose system. This ansatz goes beyond the Jastrow-Feenberg functional form and explicitly enforces coordination shells in the structure of the wavefunction. We apply this ansatz to liquid helium-4 with a simple three-variable parametrization of the pair functions. The optimized wavefunction is found to give an excellent description of the mid-range correlations in the fluid. We also demonstrate the possibility to use this ansatz to study inhomogeneous systems. The phase separation and free surface emerge naturally in this wavefunction, even though it is constructed of short-range two-body functions and does not contain one-body terms. Because no explicit description of the surface is necessary, this provides a powerful description tool for cluster states.