BEYOND THE MEAN-FIELD - QUANTUM MONTE-CARLO APPROACH FOR FINITE FERMISYSTEMS

Large-amplitude fluctuations around the mean-field are important in ho t finite Fermi systems. In the quantum Monte Carlo approach these fluc tuations are taken into account exactly but often lead to a sign probl em. A practical solution to the sign problem in the framework of the n uclear shell model allows realistic calculations in model spaces that are much larger than those that can be treated by conventional diagona lization methods. Recent applications of the Monte Carlo methods for m icroscopic calculations of collectivity and level densities in heavy n uclei are presented.