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S.T. Nakagawa, H. Nagao, G. Betz:
"An MD simulation to form an NV-N center using N_{2} implantation into diamond";
Diamond and Related Materials, 20 (2011), 927 - 930.

We have examined the dissociation process of a low-energy molecular beam making use of an empirical
molecular dynamic simulation. The main concern was to explain why two (nitrogen molecule N2) beams with
different energy (sub-keV and keV) give a similar intrapair distance RN-N in diamond. It was due to the
peculiar dependence of the lateral range straggling on the incident energy across a few keV. When a sub-keV
(N2) beam was implanted into a diamond, the dissociation elapsed a long time until it was settled in several
hundreds fs because of multiple collisions. The range distribution caused by multiple collisions is almost
isotropic whereas it becomes anisotropic when used a (N2) beam with the higher energy than that. From the
viewpoint of computation, a few keV is a critical energy to choose an algorithm MDor MC with binary collision
approximation. For the case of sub-keV N2 beam, MD is indispensable. This proved the reason of the apparent
contradiction. Much later than the collision stage, a definite change further occurred in the long-range-order
of the crystal at around 2 ps in diamond. It seems a phonon-assisted phenomenon would start then and might
affect on the further events to be occurred later than 20 ps.

Diamond NV-N center Molecular dynamics simulation Molecular beam implantation Lateral range straggling