Molecular dynamics simulation on fabrication of chiral nanoneedle by optical vortex

H Nakamura and S Habu, JAPANESE JOURNAL OF APPLIED PHYSICS, 62, SA1013 (2023).

DOI: 10.35848/1347-4065/ac91d9

We have successfully generated tantalum chiral nanoneedles in silico using three-dimensional molecular dynamics simulation to calculate the time evolution of the motion of atoms. Since current computer capabilities do not allow this nanostructure formation to be calculated at the electron level, the interaction between the optical vortex and tantalum atoms is approximated by a pseudo electric force field, which is proportional to the electric field. The embedded atom method potential "2013_eam.alloy" is used for the interatomic forces between tantalum atoms. The dependence of a topological charge and a helicity of the optical vortex beam on needle geometry, such as needle height and screw orientation, is quantitatively demonstrated. This dependence agrees with experimental measurements partially. Furthermore, we found that the presence of structure formation can be evaluated by extracting only the radial component of the force field and solving the one- dimensional equation of motion in the radial direction.

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