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

Area of Science:

• Computational Chemistry
• Quantum Chemistry
• Spectroscopy

Background:

• Accurate calculation of electric field gradients (EFG) is essential for understanding molecular properties and interactions.
• Relativistic effects become significant in molecules with heavy atoms, necessitating advanced computational methods.
• Previous methods have limitations in handling large, complex molecules with heavy elements.

Purpose of the Study:

• To present and validate the linear response elimination of the small component (LRESC) scheme for calculating EFG up to the 1/c^4 order.
• To assess the applicability of the LRESC scheme to chiral and tetrahedral molecules containing heavy halogens (Br, I, At).
• To investigate the heavy atom effect on light atoms (HALA) and environmental dependencies of EFG in these systems.

Main Methods:

• Implementation of the LRESC scheme for EFG calculations, incorporating relativistic effects up to the 1/c^4 order.
• Application to CHFClX (X = Br, I, At) chiral molecules and CHF2Br, CH2FX (X = Br, I, At) tetrahedral systems.
• Comparison of LRESC results with four-component relativistic calculations and experimental data.

Main Results:

• The LRESC scheme shows excellent agreement with four-component calculations for EFG, with minimal differences for Br and I nuclei.
• A significant heavy atom effect on light atoms (HALA) was observed for Cl and F nuclei in chiral molecules.
• Calculated nuclear quadrupole coupling constants using LRESC, including correlation effects, closely match experimental values for Cl, Br, and I.

Conclusions:

• The LRESC scheme is an effective and accurate method for calculating EFG in large, complex molecules with heavy elements.
• The study highlights the importance of relativistic effects and HALA in systems relevant to parity violation studies.
• The LRESC methodology provides a reliable tool for predicting spectroscopic parameters and advancing our understanding of molecular electronic structure.