Effect of the chemisorbed molecular structure on the frequency of carbon nanotube resonators: Molecular dynamics simulations

Tiny mass attached to the surface of carbon nanotubes (CNTs) would induce its intrinsic frequency shift. Due to their remarkable mechanical properties, such as exceptional high elastic modulus and low weight, CNTs hold significant potential as functional materials for the development of mass sensors and biosensors with atomic mass resolution. The effect of the structure of molecule covalently bonded to the surface of CNTs on its intrinsic frequency shift was investigated with full-atom molecular dynamics simulation (FAMDs), which explored the REBO potential and Lennard-Jones potential to represent the interatomic interaction. CNTs were constrained by the clamped-clamped boundary condition and the fixed-free boundary condition, respectively. In order to highlight the effect of molecular structure on the fundamental frequency of CNTs, the simulated results via the FAMDs were compared with those of additional mass molecular dynamics simulation (AMMDs), in which the mass of the attached molecule is lumped to the bonded carbon atom of CNTs. Results indicate that the structure of the covalently bonded molecular is strong enough to take effect on the frequency response of the CNT resonator.