Strong electronic polarization of the C60 fullerene by imidazolium-based ionic liquids: accurate insights from Born-Oppenheimer molecular dynamic simulations.

Fullerenes are known to be polarizable due to their strained carbon-carbon bonds and high surface curvature. The electronic polarization of fullerenes is steadily of practical importance because it leads to non-additive interactions and, therefore, to unexpected phenomena. For the first time, hybrid density functional theory (HDFT) powered Born-Oppenheimer molecular dynamics (BOMD) simulations have been conducted to observe electronic polarization and charge transfer phenomena in the C60 fullerene at finite temperature (350 K). The non-additive phenomena are fostered by the three selected imidazolium-based room-temperature ionic liquids (RTILs). We conclude that although charge transfer appears nearly negligible in these systems, electronic polarization is indeed significant, leading to a systematically positive effective electrostatic charge on the C60 fullerene: +0.14e in [MMIM][Cl], +0.21e in [MMIM][NO3], and +0.17e in [MMIM][PF6]. These results are, to a certain extent, unexpected and provide a motivation for considering novel C60-RTILs systems. HDFT BOMD is a powerful tool for investigating electronic effects in RTIL and fullerene containing nuclear-electronic systems.