Fragmentation in Molecular Clouds: The Formation of a Stellar Cluster
  The isothermal gravitational collapse and fragmentation of a molecular cloud region and the subsequent formation of a protostellar cluster is investigated numerically. The clump mass spectrum which forms during the fragmentation phase can be well approximated by a power law distribution dN/dM ~ M^(-1.5). In contrast, the mass spectrum of protostellar cores that form in the centers of Jeans unstable clumps and evolve through accretion and N-body interaction is best described by a log-normal distribution. Assuming a star formation efficiency of ~10%, it is in excellent agreement with the IMF of multiple stellar systems. 
Ralf Klessen and Andreas Burkert (MPI for Astronomy, Heidelberg,   Germany)