Optical properties of C60 vibrations.

Abstract

The tight-binding and local-density approximation (LDA) models of the electronic structure for C60 are applied to calculate the transition strength of the four infrared-active vibrations. The tight-binding results are of the correct order of magntiude, but not accurate enough to have predictive power. The LDA results give a much better description of the relative and absolute strengths of the four modes. The electron-vibration coupling in C60 is of considerable interest because of the simplicity of this system and the implications for superconductivity. The infraredactive vibrational modes acquire oscillator strength because of the coupling, raising the question of how well current models can reproduce the observed strengths. There have been two previous calculations reported of the optical properties of these vibrations, using the modified neglect of difFerential (MNDO) approximation, ' and using the local-density approximation (LDA). In this paper, we consider the local-density approximation and the tight-binding approximation, comparing the absolute magnitudes of the oscillator strengths with