Accurate ⁵⁷Fe Mössbauer Parameters from General Gaussian Basis Sets

Abstract

The prediction of isomer shifts in 57 Fe Mossbauer spectra is typically achieved by building calibration lines using the values of the density at the nuclear position. Using Slater-type orbital basis or large and specific Gaussian-type orbital basis has been thus far mandatory to achieve accurate predictions with density functional theory methods. In this work, we show that replacing the value of the density at the nucleus by the density integrated in a sphere of radius 0.06 au centered on the Fe nuclei yields excellent calibration lines ( r 2 = 0.976) with a high predictive power ( q 2 = 0.975, MAE = 0.055 mm·s –1 ) while using the conventional def2-TZVP basis set and X-ray geometrical parameters. Our data set comprises 69 57 Fe-containing compounds and 103 signals. We also find B3LYP performing significantly better than the PW91 functional.

Debye Temperature Evaluation for Secondary Battery Cathode of α-SnxFe1−xOOH Nanoparticles Derived from the 57Fe- and 119Sn-Mössbauer Spectra

“…In general, the value of isomer shift ( δ ) reflects on the 4 s electron density at the nuclear site of the Mössbauer element, which can be expressed as [ 33 ]: δ = C Δ R / R {|ψ A (0)| 2 − |ψ s (0)| 2 } where C is the constant; ∆ R and R are differences; and the average radius of Mössbauer nuclei between excited and ground states |ψ A (0)|and |ψ S (0)| are the electron density of absorber and standard, respectively. In the case of 57 Fe-Mössbauer spectroscopy, the value δ decreases when the 4 s electron density at the nuclear site increases because Δ R is negative.…”

“…In general, the value of isomer shift (δ) reflects on the 4s electron density at the nuclear site of the Mössbauer element, which can be expressed as [33]:…”