Electric Field Gradient in Chiral and Tetrahedral Molecules within High-Order LRESC Formalism.

In this work, we present the electric field gradient (EFG) given by the linear response elimination of the small component (LRESC) scheme up to the 1/ order ( is the speed of light in vacuum) in CHFClX (X = Br, I, At) chiral molecules, together with CHFBr and CHFX (X = Br, I, At) tetrahedral systems. The former could be good candidates for further parity violation studies, especially when heavy atoms are surrounding. In this context, the LRESC scheme demonstrates effective applicability to large tetrahedral and chiral molecules that incorporate heavy elements, with relativistic effects playing a crucial role.

A Relationship between the Molecular Parity-Violation Energy and the Electronic Chirality Measure.

When the weak forces producing parity-violating effects are taken into account, there is a tiny energy difference between the total electronic energies of two enantiomers (Δ), which might be the key to understanding the evolution of the biological homochirality. We focus on the electronic chirality measure (ECM), a powerful descriptor based on the electronic charge density, for quantifying the chirality degree of a molecule, in a representative set of chiral molecules, together with their energies. Our results show a novel, strong, and correlation between Δ and ECM, supporting a subtle interplay between the weak forces acting within the nuclei of a given molecule and its chirality.

High order relativistic corrections on the electric field gradient within the LRESC formalism.

In this work, we present relativistic corrections to the electric field gradient (EFG) given by the Linear Response Elimination of the Small Component (LRESC) scheme at 1/c order and including for the first time spin-dependent (SD) corrections at 1/c order. We show that these new terms improve the performance of LRESC as results with this methodology are very close to those calculated at the four-component Dirac-Hartree-Fock (4c-DHF) level. We assess the new corrections in BrY and AtY di-halogen (Y = F, Cl, Br, I, and At) and XZY bi-linear molecules (Z = Zn, Cd, and Hg; X, Y = F, Cl, Br, I, and At).

Ammonia: The molecule for establishing N and N absolute shielding scales and a source of information on nuclear magnetic moments.

Multinuclear Nuclear Magnetic Resonance (NMR) studies of the gaseous mixtures He/NH and He/NH are reported. Precise analysis of the He, N, N, and H resonance frequencies show a linear dependence on the gas density. Extrapolation of these results to the zero-pressure limit gives ν(H), ν(N), and ν(N) resonance frequencies of the isolated ammonia molecule at 300 K.