Calculation of tip-enhanced Raman spectra of carbon nanostructures

An efficient semiempirical computational methodology is developed for the simulation of Tip-Enhanced Raman Spectroscopy (TERS), by combining the discrete-dipole approximation (DDA), the bond polarizability model (BPM), and density functional theory (DFT) to describe the vibrational properties of the material system. The method is illustrated for C₆₀ whose TERS spectra are determined for different frequencies of incident illumination and for different tip shapes. The information on the local properties of the structure is correlated with the computed TERS signature, which is obtained by scanning the tip over the molecule. The method is versatile and is found to have a modest computational cost while allowing one to highlight the main features differentiating TERS from conventional Raman spectroscopy.