Local Density Functional Theory for Superfluid Fermionic Systems: The Unitary Gas

TL;DR

This paper compares ab initio calculations of superfluid fermionic systems with an extended density functional theory approach, demonstrating that SLDA accurately reproduces energies, densities, and excitation spectra in these systems.

Contribution

The paper introduces an extension of the Superfluid Local Density Approximation (SLDA) that accurately models finite and homogeneous superfluid fermionic systems, aligning with ab initio results.

Findings

SLDA reproduces total energies and density distributions.

SLDA captures the energy of the normal state.

SLDA models the excitation spectrum accurately.

Abstract

The first detailed comparison between ab initio calculations of finite fermionic superfluid systems, performed recently by Chang and Bertsch [Phys. Rev. A 76, 021603(R), (2007)] and by von Stecher, Greene and Blume [e-print arXiv:00705:0671v1], and the extension of the density functional theory Superfluid Local Density Approximation (SLDA) is presented. It is shown that SLDA reproduces the total energies, number density distributions in inhomogeneous systems along with the energy of the normal state in homogeneous systems. Unlike the Kohn-Sham LDA, in SLDA the effective fermion mass differs from the bare fermion mass and the spectrum of elementary excitations is also reproduced.