The partition function for composite systems

At high temperatures the partition function becomes sensitive to the continuum part of the level density of a composite system. In particular, nuclear partition functions play a crucial role in the final stages of stellar collapse. If the continuum part is taken into account, its effect on the partition function is to cancel the contributions made by bound states. A crude, two-fragment model which was earlier proposed, is replaced by a Fermi gas model in which the single nucleon level spectrum is truncated at the upper end while the fact that its downward extent is also finite, is taken into account properly. Calculation of level densities and partition functions is thus reduced to a constrained partition problem. Algorithms are being constructed to solve the combinational problems which arise