title: New effective interaction for the trapped fermi gas.
abstract: We apply the configuration-interaction method to calculate the spectra of two-component Fermi systems in a harmonic trap, studying the convergence of energies at the unitary interaction limit. We find that for a fixed regularization of the two-body interaction the convergence is exponential or better in the truncation parameter of the many-body space. However, the conventional regularization is found to have poor convergence in the regularization parameter, with an error that scales as a low negative power of this parameter. We propose a new regularization of the two-body interaction that produces exponential convergence for systems of three and four particles. We estimate the ground-state energy of the four-particle system to be (5.045 +/- 0.003) variant Planck's constant over 2 pi omega.
authors.affiliation: Center for Theoretical Physics, Sloane Physics Laboratory, Yale University, New Haven, CT 06520, USA.
authors.forename: Y
authors.initials: Y
authors.lastname: Alhassid
authors.forename: G F
authors.initials: GF
authors.lastname: Bertsch
authors.forename: L
authors.initials: L
authors.lastname: Fang