Design and computational evaluation of structural, electronic and optical properties of the oligomers of nC20 fullerene (n = 1–6)

Abstract

In this research, linear and non-linear oligomers of fullerene C20 oligomers with different number of units were designed and their structural, electrical and optical properties were investigated. Cohesive energy which may be a reason for the stability of oligomers was calculated that the increase in cohesive energy was seen with increasing the number of fullerene units. Linear oligomers also have more cohesive energy than their nonlinear homologous. The tendency to form a ring was observed in nonlinear oligomers, which a complete ring with perfectly symmetrical structure was obtained in a 6-membered ring. HOMO-LUMO gap (Eg) values representing electrical conductivity were calculated and in the case of linear oligomers it increased with increasing number of C20 fullerene units. Analysis of partial electrical charges and MEP diagrams showed that the two ends of the oligomers have a negative charge and the junction of fullerene units has a positive partial charge. The polarizability, α, and the first hyperpolarizability, β, were calculated and an improvement in the non-linear optical (NLO) response was observed in the C20 oligomer, so that the α values for the linear pentamer oligomer and the β value for the Config-b-A tetramer were approximately 1300 and 18,000, respectively.