title: Molecular structure, vibrational spectra, AIM, HOMO-LUMO, NBO, UV, first order hyperpolarizability, analysis of 3-thiophenecarboxylic acid monomer and dimer by Hartree-Fock and density functional theory.
abstract: In this work, the molecular structure, harmonic vibrational frequencies, UV, NBO and AIM of 3-thiophenecarboxilic acid (abbreviated as 3-TCA) monomer and dimer has been investigated. The FT-IR and FT-Raman spectra were recorded. The ground-state molecular geometry and vibrational frequencies have been calculated by using the Hartree-Fock (HF) and density functional theory (DFT)/B3LYP methods and 6-311++G(d,p) as a basis set. The fundamental vibrations were assigned on the basis of the total energy distribution (TED) of the vibrational modes, calculated with VEDA program. Comparison of the observed fundamental vibrational frequencies of 3-TCA with calculated results by HF and DFT methods indicates that B3LYP is better to HF method for molecular vibrational problems. The difference between the observed and scaled wavenumber values is very small. The theoretically predicted FT-IR and FT-Raman spectra of the title compound have been constructed. A study on the Mulliken atomic charges, the electronic properties were performed by time-dependent DFT (TD-DFT) approach, frontier molecular orbitals (HOMO-LUMO), molecular electrostatic potential (MEP) and thermodynamic properties have been performed. The electric dipole moment (μ) and the first hyperpolarizability (β) values of the investigated molecule have been also computed.
authors.affiliation: Quantum Physics Laboratory, Faculty of Sciences, University of Monastir, Monastir 5079, Tunisia.
authors.forename: Noureddine
authors.initials: N
authors.lastname: Issaoui
authors.affiliation: Quantum Physics Laboratory, Faculty of Sciences, University of Monastir, Monastir 5079, Tunisia.
authors.forename: Houcine
authors.initials: H
authors.lastname: Ghalla
authors.affiliation: Department of Physics, Sri Venkateswara College of Engineering, Sriperumbudur 602105, India. Electronic address: muthu@svce.ac.in.
authors.forename: S
authors.initials: S
authors.lastname: Muthu
authors.affiliation: Institute of Chemistry, University of Silesia, 9 Szkolna Street, 40-006 Katowice, Poland.
authors.forename: H T
authors.initials: HT
authors.lastname: Flakus
authors.affiliation: Quantum Physics Laboratory, Faculty of Sciences, University of Monastir, Monastir 5079, Tunisia; Faculty of Science, King Abdulaziz University, Saudi Arabia.
authors.forename: Brahim
authors.initials: B
authors.lastname: Oujia
keywords: 3-Thiophenecarboxylic acid; DFT; FTIR; HOMO–LUMO