Effects of different basis sets and donor‐acceptor groups on linear and second‐order nonlinear optical properties and molecular frontier orbital energies

Abstract

ABSTRACT:The calculation of molecular hyperpolarizability, molecular frontier orbital energies of some donor-acceptor oxadiazoles (5a-f, 8a-f, and 9a-f) have been investigated using ab initio methods and different basis sets. Ab initio optimizations were performed at the Hartree-Fock (HF) and density functional (Beckee-3-Lee-YangParr; B3LYP) levels of theory with 6-31G basis set. The polarizability (Ͻ␣Ͼ), anisotropy of polarizability (⌬␣), and ground-state dipole moment (), first hyperpolarizability (␤), and molecular frontier orbital (HOMO, highest occupied molecular orbital and LUMO, lowest unoccupied molecular orbital) energies of 5a-f, 8a-f, and 9a-f have been calculated at the HF and B3LYP methods with 6-31G, 6-31G(d), 6-31ϩG(d), 6-31ϩϩG(d,p), 6-311G, 6-311G(d), 6-311ϩG(d), and 6-311ϩϩG(d,p) basis sets. Also, the molecular hardness () and electronegativity () parameters have been obtained using molecular frontier orbital energies. The Ͻ␣Ͼ, ⌬␣, , ␤, HOMO, LUMO energies, and parameters have been investigated as dependence on the choice of method and basis set. The variation graphics of Ͻ␣Ͼ, ⌬␣, , ␤, , and parameters using HF and B3LYP methods with different basis sets are presented. We have examined the frontier molecular orbital pictures of 5a-f, 8a-f, and 9a-f using B3LYP/6-31ϩϩG(d,p) level. The 5a-f, 8a-f, and 9a-f display significant linear, second-order molecular nonlinearity, and molecular parameters and provide the basis for future design of efficient nonlinear optical materials having the 1,3,4-oxadiazole core.

A theoretical study on 2-chloro-5-(2-hydroxyethyl)-4-methoxy-6-methylpyrimidine by DFT/ab initio calculations

“…Obtained hyperpolarizability values show that the title molecule exhibits considerable NLO character as compared to previously calculated molecules [53][54][55]. …”

“…In this regard, DFT and HF methods have been used to calculate the ground state molecular structure [19], bonding features, conformational study [20], natural bond orbital (NBO) [21] and nonlinear optical (NLO) [22] analysis, 1 H and 13 C NMR chemical shifts [23], molecular frontier orbital energies [24][25][26], Mulliken and NBO charges as well as the molecular electrostatic potential (MEP) map [27] for the title molecule.…”

A Theoretical Study on Structural, Spectroscopic, Electronic and Nonlinear Optical Properties of 1-[(E)-{[4-(Morpholin-4-Yl)Phenyl]Imino}Methyl]Naphthalen-2-Ol

“…The total energy, HOMO and LUMO energies, the energy gap (ΔE), ionization potential (I), electron affinity (A), absolute electronegativity (χ), absolute hardness (η), and softness (S) for the MPIMN molecule have been calculated at B3LYP and B3PW91 functionals, and the results are given in Table 5. Electronegativity (χ) and chemical hardness (η) can be calculated using the frontier molecular orbital energies [58][59][60]. Electronegativity, chemical hardness, and chemical softness can be calculated by using HOMO and LUMO energy values for the title compound [61].…”

Optimized geometry, vibration (IR and Raman) spectra and nonlinear optical activity of p-nitroanilinium perchlorate molecule: A theoretical study

“…The soft molecules are more polarizable than the hard ones since they need small energy to excite one electron from a ground state to excited state. Electronegativity (χ) and chemical hardness (η) can be calculated using the frontier molecular orbital energies [38,39]. The χ and η values were calculated as 5.9555 and 2.2775 eV at B3LYP level (Table 6).…”