Bardak F.Bardak C.Karaca C.Kose E.Bilgili S.Atac A.2024-07-222024-07-22202201677322http://akademikarsiv.cbu.edu.tr:4000/handle/123456789/13005Nonlinear optical phenomena play significant roles in the bulk properties and responsive characteristics of ionic liquids, especially when used under strong electric fields. The variability of the anion-cation pair in ionic liquids makes them designer solvents; thus, the anion or cation dependency of the physicochemical properties should be understood in depth. Accordingly, the electric field-induced characteristics of eight ionic liquids with [Br]−, [BF4]−, [PF6]−, [Ac]−, [TFAc]−, [MS]−, [NTf2]−, and [Tos]− anions paired with the 1-butyl-3-methyl imidazolium cation were investigated using density functional theory modeling at four theoretical levels: B3LYP-6-31G(d), M06-2X 6-31G(d), M06-2X 6-311++G(d,p), and M06-2X aug-cc-PVTZ. The frontier molecular orbitals, electrostatic potential surface, and electron density difference maps were obtained to visualize the electrostatic characteristics. The permanent electric dipole moment, linear electric polarizability, and first-order and second-order hyperpolarizabilities were also determined. While the static dipole moment and dipole polarizabilities could be obtained using low-level quantum chemistry at a satisfactory level, the functionalization of more intensive methods was required to accurately obtain the nonlinear optical properties. © 2021 Elsevier B.V.EnglishDensity functional theoryDipole momentElectric fieldsMolecular orbitalsNegative ionsNonlinear opticsOptical propertiesPhysicochemical propertiesPositive ionsBulk propertiesDensity-functional-theoryElectric field inducedHyperpolarizabilitiesImidazolium cationNonlinear optical phenomenonNonlinear optical propertiesPhysicochemical propertyStrong electric fieldsTheory modelIonic liquidsArticle10.1016/j.molliq.2021.117030