We analyze the role of different equations of state and momentum dependent
interactions in fragmentation. Heavy ion collisions are simulated using a q
uantum molecular dynamics model and fragments are constructed with the mini
mum spanning tree method. A detailed study is carried out for Xe+Sn reactio
ns at incident energies E=100 and 400 MeV/nucleon and over a wide range of
impact parameters. Our analysis indicates that the light mass fragments in
central collisions are sensitive towards different static equations of stat
e whereas the heavy fragments are insensitive towards different static equa
tions of state. The results with momentum dependent interactions are quite
different. Now, the heavy fragments are also sensitive towards different eq
uations of state. The momentum dependence of the equation of state is able
to break the spectator matter into a large number of fragments at periphera
l collisions whereas a simple static equation of state fails to produce any
fragments. As a result, the properties of fragments (such as transverse fl
ow, rapidity distribution, etc.) are also affected by the momentum dependen
ce of the interaction. [S0556-2813(99)05110-9].