Concept of effective states of atoms in compounds to describe properties determined by the densities of valence electrons in atomic cores

TL;DR

This paper introduces a novel method for describing atomic electronic states in compounds, enabling accurate predictions of properties influenced by core electrons, with applications to hyperfine structure, symmetry violations, and X-ray emission shifts.

Contribution

The paper proposes a new approach for modeling effective atomic states in compounds, improving agreement with experimental data and computational efficiency within relativistic pseudopotential frameworks.

Findings

Achieved good quantitative agreement with experimental data.

Successfully interpreted chemical shifts in X-ray emission lines.

Demonstrated computational efficiency for heavy-atom systems.

Abstract

A new approach for describing the effective electronic states of "atoms in compounds" to study the properties of molecules and condensed matter which are circumscribed by the operators heavily concentrated in atomic cores is proposed. Among the properties are hyperfine structure, space parity (P) and time reversal invariance (T) nonconservation effects, chemical shifts of x-ray emission lines (XES), M\"{o}ssbauer effect, etc. Advantage of the approach is that a good quantitative agreement of predicted and experimental data can be attained even for such difficult cases as XES chemical shifts providing correct quantum-mechanical interpretation of the experimental data. From computational point of view the method can be quite efficient being implemented in the framework of the relativistic pseudopotential theory [Int.J. Quantum Chem. 71, 359 (1999)] and procedures of recovering the wave functions in heavy-atom cores [Int.J. Quantum Chem. 104, 223 (2005)] after a molecular, cluster or periodic structure calculation performed on the basis of pseudoorbitals smoothed near the nuclei within the pseudopotential approximation. We report results of our studies of a number of atomic and molecular systems to demonstrate the capabilities of the approach.