Features of chemical bonds based on the overlap polarizabilities: diatomic and solid-state systems with the frozen-density embedding approach

Abstract

The chemical bond overlap properties were obtained for alkali halides NaY (Y = F, Cl, Br), alkaline-earth chalcogenides MX (M = Ca, Mg and X = O, S, Se) and alkali and alkali-earth metals (Li, Na, and Mg) in diatomic and solid-state systems using an embedding approach based on the frozen density functional theory to simulate the crystalline effects. The computational protocol established provides errors for bond distances smaller than 1%. The results indicate that larger chemical bond covalency leads to larger absorption or scattering by the overlap region. The ionic specific valence and overlap polarizability are closely related to the valence orbital compactness measured by the sum of Mulliken electronegativities. The embedding approach used in this work makes it possible to quantify the effects of the crystalline environment on the chemical bond overlap properties. In the solid-state, the bond overlap charges are less polarizable, in cases of well-known ionic systems (provided by electronegativity differences), leading to smaller chemical bond covalency in solids than in diatomics. The spectroscopic properties of the polarizability of the electron density in the overlap region of a chemical bond could be measured in the 1-20 eV spectral region and could be used to characterize some bands in several spectra whose assignments are ambiguous or not available.

New Luminescent Lanthanide Tetrakis‐Complexes NEt4[LnL4] Based on Dimethyl‐N‐Benzoylamidophosphate

“…The overlap polarizabilities are quantities related to the degree of covalency of the Ln–Ligating atom chemical bond, and can be given by: [94,98,99] …”

Theoretical and Experimental Investigation of the Tb3+ → Eu3+ Energy Transfer Mechanisms in Cubic A3Tb0.90Eu0.10(PO4)3 (A = Sr, Ba) Materials

“…The overlap polarizabilities α OP are quantities related to the covalent fraction of a chemical bond, ,− and it is given by where e is the electron charge, R is the length of the bond, and Δ ε is an excitation energy associated with the chemical bond.…”

Decoding Chemical Bonds: Assessment of the Basis Set Effect on Overlap Electron Density Descriptors and Topological Properties in Comparison to QTAIM

“…QTAIM is widely adopted to yield information about features of chemical bonding using a simple post-SCF treatment ,,− with low computational cost. On the other hand, OP descriptors have been utilized ,− mainly for studying different systems (diatomics, solids, and lanthanide-based compounds) and were recently extended to a proper treatment of molecular systems using LMOs. ,, While QTAIM basis set dependency is a recurring subject in the literature, − ,− the dependence of OP chemical bond descriptors on the basis functions has not been reported yet.…”

“…Originally designed to analyze diatomic (or diatomic-like) systems, the OP model was primarily used to describe Ln–L bonds in lanthanide complexes . However, it has since been successfully applied to a range of systems, including diatomics, molecular, coordination compounds, and solid-state materials. − Understanding the overlap polarizability is key to understanding the relationship between 4f–4f transition intensities and the Ln–L covalent character. − The OP model has also been expanded to calculate overlap properties in polyatomic molecules through localized molecular orbitals, such as the Pipek–Mezey localization method, which can be done using various atomic charge partitioning methods, including Mulliken, Löwdin, Hirshfeld, Bader, and Becke populations . Moreover, the OP approach has been applied to describe chemical bonding in organic reaction systems, yielding results in excellent agreement with other chemical bonding analysis models, such as QTAIM and LVM. − …”