Refractive indices of organo‐metallic and ‐metalloid compounds: A long‐range corrected DFT study

Abstract

Refractive indices of metal- and metalloid-containing compounds are systematically evaluated using the Lorentz-Lorenz equation with polarizabilities obtained via density functional theory (DFT). Among exchange-correlation functionals studied, the long-range corrected (LC) fuctionals yield the lowest errors for the polarizabilities of gaseous compounds and refractive indices of liquids. The LC-DFT predicts very well the wavelength dependence of refractive indices. A scheme for computing Abbe numbers of organometallic and organometaloid compounds is proposed and a refractive index - Abbe number plot for 80 compounds is constructed. The compounds containing heavier metals tend to have higher refractive index and lower Abbe number, but several outliers, among them Te(CH ) , Ni(PF ) , Sb(C F ) , Hg(C F ) , are found. For Hg(C F ) , also the effect of intramolecular and intermolecular degrees of freedom on polarizability is investigated. The absolute relative error in polarizability decreases from 5.7% for monomer model to 1.7% when a dimer model (derived from the available experimental crystal data) is employed. © 2016 Wiley Periodicals, Inc.

Local structure and hydrogen bond characteristics of imidazole molecules for proton conduction in acid and base proton-conducting composite materials

“…All DFT calculations were performed at the CAM-B3LYP/aug-cc-pVTZ level for models A, B, F, and G, and aug-cc-pVDZ for models C, D, and E using the Gaussian 09 software package. 30 The performance of long-range-corrected hybrid functionals was perspective, 31 and the functionals were used for a wide range of application systems [32][33][34] such as Nafion membranes, 35 NMR shifts, 36 and proton transfer in proton-conducting materials. 37 CAM-B3LYP 38 is a long-range-corrected version of B3LYP that employs the Coulomb-attenuating method and has performed well in the case of hydrogen bonding characteristics.…”

Solvation Effects on Polarizability of Aromatic Fluids

“…The model could be useful for predicting optical and dielectric properties of highly polarizable systems. The results presented here suggest that the very good approximation of the total polarizability of moderately polarizable liquids by electronic polarizability − is due to the compensation of solvation and vibrational contributions.…”

“…The changes in F LL reflect the dependence of polarizability on solvation strength, the latter depending on fluid density. For moderately polarizable substances, these changes are modest and similar to the magnitude of errors resulting from modeling. − On the other hand, in highly polarizable systems such as ionic liquids, significant nonadditive effects have been reported …”

“…We consider the following polarizability model α = α 1 normale + normalΔ α solv + normalΔ α normalv The major contribution to eq is the electronic polarizability of an isolated molecule, α 1 e . For aromatic substances, it is represented very well − by the long-range corrected (LC) DFT, , such as LC modifications of pure BLYP and PBE functionals, LC-BLYP and LC-PBE, respectively. The second term in the r.h.s.…”

“…Predicting the RI or optical dielectric constant, ε r , is therefore important for efficient development of such materials. Various data-driven and physics-based approaches focusing on predicting RI and related quantities have been proposed. − Often the Lorentz–Lorenz equation is used n 2 − 1 n 2 + 2 = 4 π N normalA 3 α V where, α is the molecular polarizability, N A is the Avogadro number, and V is the molar volume. Although α is often assumed to be independent of the condensed phase state parameters, the Lorentz–Lorenz function, F LL = ρ –1 ( n 2 – 1)/( n 2 + 2), depends weakly on density: <1% for ethane, 0.5% for sulfur hexafluoride, 1% for xenone, and 2.5% for 1,1-difluoroethane .…”