OICC Press Journal of Theoretical and Applied Physics 2251-7235 17 1 2023 11 17 Theoretical investigation of structural, electronical, and optical properties of [18] DBA annulene and its derivatives 10.57647/j.jtap.2023.1701.01 EN Mohammad Hossein Fekri Department of Chemistry, Ayatollah Borujerdi University, Borujerd, Iran 0000-0002-1305-1902 Niko Karimpoor Department of Chemistry, Ayatollah Borujerdi University, Borujerd, Iran Motaleb Ghasemian Department of Chemistry, Ayatollah Borujerdi University, Borujerd, Iran Samaneh Soleymani Department of Chemistry, Ayatollah Borujerdi University, Borujerd, Iran Maryam Razavi Mehr Department of Chemistry, Ayatollah Borujerdi University, Borujerd, Iran Journal Article 2023 11 17 The structure geometry, vibrational frequencies, electronic and optical properties of a series of donor-acceptor substituted dodecadehydrotribenzo [18] annulenes ([18] DBA) were investigated using the B3LYP method at a 6-31+G (d, p) basis set. After optimization of the structures, HOMO and LUMO energies, gap energy (Eg), global hardness (η), chemical potential (μ), electrophilicity index (ω), maximum charge transfer (∆Nmax), electronegativity (χ), Fermi level (EFL), wavelength (λ), oscillator power (f0), and participation percentage (% Con) for [18] DBA derivatives. A significant increase in the first hyperpolarizability was observed by substitution on [18] DBA. The results of this study may be used to design and construct materials with adjustable electrical properties. The results indicate that the NLO response of [18] DBA could be enhanced by functionalizing different substitutions. In general, the NLO response and electronic properties of the S1-10 are more excellent than others.