  Fullerene coalescence experimentally found in fullerene-embedded single-wall
nanotubes under electron-beam irradiation or heat treatment is simulated by
minimizing the classical action for many atom systems. The dynamical trajectory
for forming a (5,5) C$_{120}$ nanocapsule from two C$_{60}$ fullerene molecules
consists of thermal motions around potential basins and ten successive
Stone-Wales-type bond rotations after the initial cage-opening process for
which energy cost is about 8 eV. Dynamical paths for forming large-diameter
nanocapsules with (10,0), (6,6), and (12,0) chiral indexes have more bond
rotations than 25 with the transition barriers in a range of 10--12 eV.
