  We simulate the central reactions of $^{20}$Ne+$^{20}$Ne,
$^{40}$Ar+$^{45}$Sc, $^{58}$Ni+$^{58}$Ni, $^{86}$Kr+$^{93}$Nb,
$^{129}$Xe+$^{118}$Sn, $^{86}$Kr+$^{197}$Au, and $^{197}$Au+$^{197}$Au at
different incident energies for different equations of state, different binary
cross sections and different widths of Gaussians. A rise-and-fall behavior of
the multiplicity of intermediate mass fragments (IMFs) is observed. The system
size dependence of peak center-of-mass energy E$_{c.m.} ^{max}$ and peak IMF
multiplicity $<$N$_{IMF}>^{max}$ is also studied, where it is observed that
E$_{c.m.}^{max}$ follows a linear behavior and $<$N$_{IMF}>^{max}$ shows a
power-law dependence. A comparison between two clusterization methods, the
minimum spanning tree and the minimum spanning tree method with binding energy
check (MSTB), is also made. We find that the MSTB method reduces the
$<$N$_{IMF}>^{max}$, especially in heavy systems. The power-law dependence is
also observed for fragments of different sizes at E$_{c.m.} ^{max}$ and the
power-law parameter $\tau$ is found to be close to unity in all cases except
A$^{max}$.
