title: Effects of density functionals and dispersion interactions on geometries, bond energies and harmonic frequencies of EUX3 (E=N, P, CH; X=H, F, Cl).
abstract: Quantum-chemical calculations have been performed to evaluate the geometries, bonding nature and harmonic frequencies of the compounds [EUX3] at DFT, DFT-D3, DFT-D3(BJ) and DFT-dDSc levels using different density functionals BP86, BLYP, PBE, revPBE, PW91, TPSS and M06-L. The stretching frequency of UN bond in [NUF3] calculated with DFT/BLYP closely resembles with the experimental value. The performance of different density functionals for accurate UN vibrational frequencies follows the order BLYP>revPBE>BP86>PW91>TPSS>PBE>M06-L. The BLYP functional gives accurate value of the UE bond distances. The uranium atom in the studied compounds [EUX3] is positively charged. Upon going from [EUF3] to [EUCl3], the partial Hirshfeld charge on uranium atom decreases because of the lower electronegativity of chlorine compared to flourine. The Gopinathan-Jug bond order for UE bonds ranges from 2.90 to 3.29. The UE bond dissociation energies vary with different density functionals as M06-L<TPSS<BLYP<revPBE<BP86<PBE≈PW91. The orbital interactions ΔEorb, in all studied compounds [EUX3] are larger than the electrostatic interaction ΔEelstat, which means the UN bonds in these compound have greater degree of covalent character (in the range 63.8-77.2%). The UE σ-bonding interaction is the dominant bonding interaction in the nitride and methylidyne complexes while it is weaker in [PUX3]. The dispersion energy contributions to the total bond dissociation energies are rather small. Compared to the Grimme's D3(BJ) corrections, the Corminboeuf's dispersion corrections are larger with metaGGA functionals (TPSS, M06-L) while smaller with GGA functionals.
authors.affiliation: School of Chemical Sciences, Devi Ahilya University Indore, Khandwa Road Campus, Indore 452 001, India. Electronic address: kkpandey.schem@dauniv.ac.in.
authors.forename: Krishna Kumar
authors.initials: KK
authors.lastname: Pandey
authors.affiliation: School of Chemical Sciences, Devi Ahilya University Indore, Khandwa Road Campus, Indore 452 001, India.
authors.forename: Pankaj
authors.initials: P
authors.lastname: Patidar
authors.affiliation: School of Chemical Sciences, Devi Ahilya University Indore, Khandwa Road Campus, Indore 452 001, India.
authors.forename: Sunil Kumar
authors.initials: SK
authors.lastname: Patidar
authors.affiliation: School of Chemical Sciences, Devi Ahilya University Indore, Khandwa Road Campus, Indore 452 001, India.
authors.forename: Ravi
authors.initials: R
authors.lastname: Vishwakarma
mesh_terms: D056831:Coordination Complexes / Q000737:chemistry*; D004583:Electrons; D008958:Models, Molecular; D011789:Quantum Theory; D014501:Uranium / Q000737:chemistry*
chemical_list: D056831:Coordination Complexes; D014501:Uranium
keywords: Bonding; DFT; Dispersion; Uranium; Vibrational frequencies