Absence of Wigner molecules in one-dimensional few-fermion systems with   short-range interactions
  We study by means of exact-diagonalization techniques the ground state of a few-fermion system with strong short-range repulsive interactions trapped by a harmonic potential in one spatial dimension. Even when the ground-state density profile displays at strong coupling very well pronounced Friedel oscillations with a `4k_F periodicity', the pair correlation function does not show any signature of Wigner-molecule-type correlations. For the sake of comparison, we present also numerical results for few-electron systems with Coulomb interactions, demonstrating that their ground state at strong coupling is, on the contrary, a Wigner molecule. 
Jing-Jing Wang, Wei Li, Shu Chen, Gao Xianlong, Massimo Rontani, Marco   Polini
cond-mat.str-el