An empirical force field for the simulation of the vibrational spectroscopy of carbon nanomaterials

Abstract

An empirical force field for carbon based upon the Murrell-Mottram potential is developed for the calculation of the vibrational frequencies of carbon nanomaterials. The potential is reparameterised using data from density functional theory calculations through a Monte-Carlo hessian-matching approach, and when used in conjunction with the empirical bond polarisability model provides an accurate description of the non-resonant Raman spectroscopy of carbon nanotubes and graphene. With the availability of analytical first and second derivatives, the computational cost of evaluating harmonic vibrational frequencies is a fraction of the cost of corresponding quantum chemical calculations, and makes the accurate atomistic vibrational analysis of systems with thousands of atoms possible. Subsequently, the non-resonant Raman spectroscopy of carbon nanotubes and graphene, including the role of defects and carbon nanotube junctions is explored.

Simulation of the Raman spectroscopy of multi-layered carbon nanomaterials

“…Recently, we reparameterised the MM potential to describe the structure and vibrational frequencies of carbon nanomaterials using a Monte-Carlo hessian-matching approach to reproduce data from DFT calculations. 42 This potential was applied to study the vibrational spectroscopy of single-walled carbon nanotubes and graphene.…”

“…40,41 Recently, we introduced an empirical model for the simulation of the Raman spectroscopy of carbon nanomaterials in which the Murrell-Mottram potential was reparameterised to reproduce the DFT structure and Hessian matrix of C 60 . 42 The harmonic frequencies calculated using this potential are combined with Raman intensities computed using the bond polarisation model (BPM) 43 and allowed the Raman spectra of carbon materials consisting of several thousand carbon atoms to be simulated. Subsequently, the role of defects on the Raman spectroscopy of CNTs and graphene, and the Raman spectroscopy of carbon nanotube junctions were studied.…”

Structural characterization of carbon nanotubes via the vibrational density of states

“…Semiempirical methods have recently been shown to correspond fairly well with experiments. 46,47 The vibrational density of states (VDOS) can well be used to determine many chemical and physical properties of carbon nanotubes. Besides studying chirality and defects, the VDOS can also be used to calculate thermal conductivity.…”

Vibrational Analysis of Carbon Nanotube-Based Nanomechanical Resonators

“…Previous work has shown that widely used potentials such as REBO perform poorly for the prediction of vibrational frequencies of fullerenes and CNTs, 29 but new potentials designed to predict vibrational frequencies of carbon nanostructures have been reported. 30 In this work, a vibrational frequency analysis is performed for the three types of nanomechanical resonators illustrated in Figure 1. Using an empirical atomistic model, the vibrational modes of the different types of nanoresonators and their dependence on the dimensions of the nanotube are characterized.…”