Effect of Cage Charges on Multiphoton Absorptions: First-Principles Study on Metallofullerenes Sc2C2@C68 and Sc3N@C68

摘要

A combined method of the time-dependent density functional theory (TDDFT) and sum-overstate (SOS) formula was implemented to model multiphoton absorption spectra, including two-photon absorption (2PA) and three-photon absorption (3PA), of Sc2C2@C68 and Sc3N@C68 endohedral metallofullerenes (EMFs). This method has been proved to be effective by comparisons between the calculated and experimental results of trans-4,4′-bis[diphenylamino]stilbene. It was found that the multiphoton absorption cross sections were larger for Sc2C2@C68 than that of Sc3N@C68. The electronic origin of multiphoton absorption has been identified with respect to the molecular orbitals involved in charge transfer process. It shows that the increase of π-charges on the cage of C68 results in a large multiphoton absorption cross section in EMFs.