ON THE USE OF THE WHOLE EIGENVALUE SPECTRUM TO OBTAIN SINGLE MOLECULE BAND STRUCTURES AND SOLID BAND GAPS FOR MOLECULAR ELECTRONICS STUDIES

Abstract

A Density Functional microscopic model of C60, consisting of seven molecular orbitals (3 occupied and 4 empty), was employed to get the best values for the half-width and the scanning distance of the mathematical function used to obtain the theoretical DOS spectrum. It is found that the convolution of the whole eigenvalue spectrum with a Gaussian function should be made with values of 0.1 eV for both, the broadening parameter and the scanning distance. The theoretical calculation of the VB-CB band gap for the solid from results belonging to isolated C60 is in a relatively good agreement with most results. We were able to simulate the experimental band gap starting from the theoretical DOS spectrum and using some data. Regarding the HOMO-LUMO gap, the isolated molecule results are in very good agreement with results for solid C60. Finally it is suggested that experimentalists select their results based on an a priori knowledge of theoretical results because they intend to calculate some properties needing them