Effect of THz electric field on 5CB in the presence of acetonitrile and acetone and its dynamical behaviour in these polar solvents: a DFT and MD simulation study

Abstract

The electro-optical, NLO, electronic and global reactivity descriptors of 5CB LC molecule have been investigated under the influence of external terahertz (THz) electric field in different solvent environments such as acetonitrile and acetone using DFT-based LC-BLYP/6-311+G(d,p) technique. Structural and dynamical characteristics of 5CB in both the polar solvents have been carried out using MD simulations. Radial distribution functions (RDFs) have been analysed to examine solute–solvent interactions, while the calculation of mean square displacement (MSD) and diffusion coefficient (D) elicits molecular mobility. Enhanced electro-optical, NLO, electronic and global reactivity descriptor parameters in both the polar solvents under the application of THz field are observed. RDF analysis reveals strong short-range coordination of the cyano group of 5CB in both the polar solvents, with the first peak at 3.55 Å in 5CB–acetonitrile and at 3.15 Å in 5CB–acetone, which are consistent with hydrogen bonding and dipole–dipole interactions. MSD outcome exhibits increased translational motion of 5CB molecules in acetonitrile as compared to acetone medium, reflecting weaker solvent–solute interaction in 5CB–acetonitrile solution, which is further evidenced by the diffusion coefficient plot.