Time-resolved fragmentation cross-section simulation of C60++C60 collisions.

Abstract

We have performed density functional theory--linear combination of atomic orbitals molecular-dynamics statistical trajectory ensemble simulations of the 500 eV cross-beam collision of ${\mathrm{C}}_{60}^{+}$+${\mathrm{C}}_{60}$, where the charged collision partner is thermally excited with an average vibrational energy of 30 eV. The time-resolved fragmentation cross section shows the immediate sputtering of carbon dimers, and the formation of small fragments (N\ensuremath{\le}9) during the early stage of collision where there are still large cluster compounds (110\ensuremath{\le}N\ensuremath{\le}120). Medium-size cluster fragments (N\ensuremath{\approxeq}10--40) are formed mainly at the very end of the collision, i.e., as products of a multifragmentation process. The mean coordination number cross section is introduced as a means of characterizing structures of fragmentation products. Though our simulation statistics are calculated from a limited number of trajectories only (n=96--1024), odd-even alterations in the fragmentation cross section are clearly resolved.