Long‐Range Corrected DFT Calculations of First Hyperpolarizabilities and Excitation Energies of Metal Alkynyl Complexes. Issue 12 (2nd May 2018)

• Record Type: Journal Article
• Authors: Kodikara, Mahesh S.; Stranger, Rob; Humphrey, Mark G.
• Is Part Of: Chemphyschem. Volume 19:Issue 12(2018)
• Page Start: 1537
• Page End: 1546
• Publication Date: 2018-05-02
• Subjects: density functional calculations -- excitation energy -- nonlinear optics -- organometallics -- transition metals; Chemistry, Physical and theoretical -- Periodicals; 541.05
• DOI: 10.1002/cphc.201701052
• Languages: English
• ISSNs: 1439-4235

Abstract

Abstract: The performance of the CAM‐B3LYP, ω B97X and LC‐BLYP long‐range corrected density functional theory methods in the calculation of molecular first hyperpolarizabilities (β) and low‐lying charge transfer (CT) excitation energies of the metal alkynyl complexes M(C≡C‐4‐C6 H4 ‐1‐NO2 )(κ 2 ‐dppe)(η 5 ‐C5 H5 ) [M=Fe (1 ), Ru (2 ), Os (3 )] and trans ‐[Ru{C≡C‐(1, 4‐C6 H4 C≡C)n ‐4‐C6 H4 ‐1‐NO2 }Cl(κ 2 ‐dppm)2 ] [ n =0 (4 ), 1 (5 ), 2 (6 )] was assessed. The BLYP, B3LYP and PBE0 standard exchange‐correlation functionals and the Hartree‐Fock method were also examined. The BLYP functional was shown to perform poorly in the calculation of β and low‐energy CT transitions. The hybrid functionals (B3LYP and PBE0) showed significant improvement over the pure functional BLYP, but overestimated the hyperpolarizability ratios and the wavelengths of the lowest energy metal‐to‐ligand CT transitions for5 and6 . The effect of long‐range corrections is noteworthy, particularly for the larger complexes, improving the calculation of β ratios for4–6 . However, CAM‐B3LYP, ω B97X, and LC‐BLYP considerably overestimated the low‐lying CT energies. PBE0 was found to give the best transition energy match for4 . The influence of the phenylene ring orientation in the alkynyl ligand on the calculated properties is substantial, particularly for the larger complexes. For these types of calculations, a basis set with diffuse functions (at least 6‐31+G(d)) for the heavy elements is recommended. Abstract : Old versus new : A comparison between different DFT functionals, including recently introduced long‐range corrected and conventional DFT methods, is made in the calculation of first hyperpolarizabilities and excitation energies of low‐lying charge‐transfer transitions in metal alkynyl complexes.