Design of novel molecular switches using the C20 & C40 nanobud

Abstract

A molecular switch is a molecule that can reversibly switch between two or more stable states under the influence of environmental factors such as electric current or field, presence of other ions, ligands, pH change, light, etc. Using density functional theory calculations at B3LYP, M06-2X, WB97XD and B3LYP-D3 computational level, we investigate the possibility of using C20 & C40 nanobud as a molecular switch. For this purpose, the effect of different electric fields (0, 0.002, 0025, 0.003, 0.004 and 0.006 a.u.) on structural, electrical and nonlinear optical properties was investigated. It was shown that with the increase of the electric field, the dihedral angle and the bond length of the molecule changes greatly, and a sudden change in the dihedral angle can indicate the switch become ON. Also, with the increase of the electric field, the distance between the HOMO and LUMO orbitals decreases, and this changes increased greatly in a certain range of the electric field, which indicates the change of the state of the molecular switch to ON. The effect of the field on the optical properties of the switch also showed that with the increase in the intensity of the field, the values of α, β and μ increased, and this change was in a specific range of a very strong electric field, which corresponds exactly to the change of the dihedral angle and the behavior of HLG. The M06-2X, WB97XD and B3LYP-D3 methods were used to check the accuracy of the data, and it was shown that the results of these two methods are approximately the same as the results of the calculations related to the B3LYP method.