Monte Carlo calculations for Fermi gases in the unitary limit with a   zero-range interaction
  An ultracold Fermi gas with a zero-range attractive potential in the unitary limit is investigated using variational and diffusion Monte Carlo methods. Previous calculations have used a finite range interactions and extrapolate the results to zero-range. Here we extend the quantum Monte Carlo method to directly use a zero-range interaction without extrapolation. We employ a trial wave function with the correct boundary conditions, and modify the sampling procedures to handle the zero-range interaction. The results are reliable and have low variance. 
Renato Pessoa and S. A. Vitiello and K. E. Schmidt
cond-mat.quant-gas