  Because of thermal expansion and residual interactions, hot nuclear fragments
produced in multifragmentation reactions may have lower nucleon density than
the equilibrium density of cold nuclei. In terms of liquid-drop model this
effect can be taken into account by reducing the bulk energy of fragments. We
study the influence of this change on fragment yields and isotope distributions
within the framework of the statistical multifragmentation model. Similarities
and differences with previously discussed modifications of symmetry and surface
energies of nuclei are analyzed.
