Sputtering of octatetraene by 15Â keV C60 projectiles: Comparison of reactive interatomic potentials

- Probing the effect of interatomic potentials on sputtering of an octatetraene sample.
- Problems with charge calculations are observed during cluster impact for ReaxFF.
- COMB3 leads to a very low sputtering yield due to abrupt energy dissipation.
- AIREBO is computationally the most efficient, while ReaxFF is more accurate.

Molecular dynamics computer simulations have been used to probe the effect of the AIREBO, ReaxFF and COMB3 interatomic potentials on sputtering of an organic sample composed of octatetraene molecules. The system is bombarded by a 15 keV C60 projectile at normal incidence. The effect of the applied force fields on the total time of simulation, the calculated sputtering yield and the angular distribution of sputtered particles is investigated and discussed. It has been found that caution should be taken when simulating particles ejection from nonhomogeneous systems that undergo significant fragmentation described by the ReaxFF. In this case, the charge state of many particles is improper due to an inadequacy of a procedure used for calculating partial charges on atoms in molecules for conditions present during sputtering. A two-step simulation procedure is proposed to minimize the effect of this deficiency. There is also a possible problem with the COMB3 potential, at least at conditions present during cluster impact, as its results are very different from AIREBO or ReaxFF.