Crossover from fermi liquid to Wigner molecule behavior in quantum dots

The crossover from weak to strong correlations in parabolic quantum dots at zero magnetic field is studied by numerically exact path-integral Monte Ca rlo simulations for up to eight electrons. By the use of a multilevel block ing algorithm, the: simulations are carried out free of the fermion sign pr oblem. We obtain a universal crossover governed only by the density paramet er r(s). For r(s) > r(c), the data are consistent with a Wigner molecule de scription, while, for r(s) < r(c), Fermi liquid behavior is recovered. The crossover value r(c) approximate to 4 is surprisingly small. [S0031-9007(99 )08929-2].