  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.

Astrophysics