Multireference study of spin-orbit coupling in the hydrides of the 6p-block elements using the model core potential...

Area of Science:

• Computational Chemistry
• Quantum Chemistry
• Relativistic Effects

Background:

• Late p-block elements exhibit significant relativistic effects impacting their electronic structure.
• Accurate theoretical treatment of spin-orbit coupling is crucial for understanding these elements.

Purpose of the Study:

• Develop and validate model core potentials (MCPs) for late p-block elements (Tl-Rn) and their hydrides.
• Assess the accuracy of MCPs for spin-orbit multireference calculations.
• Evaluate the computational efficiency of the developed MCPs.

Main Methods:

• Developed novel model core potentials incorporating scalar-relativistic and spin-orbit coupling effects.
• Employed Douglas-Kroll relativistic treatment.
• Performed spin-orbit multireference configuration interaction and perturbation theory calculations.

Main Results:

• MCPs demonstrate high accuracy, with errors within meV for dissociation energies and 30 cm⁻¹ for vibrational frequencies compared to all-electron calculations.
• Established maximum error limits for MCPs across np-block elements (n=2-6).
• Achieved significant computational speedups (20-fold for CI, 6-fold for MRPT).

Conclusions:

• The developed MCPs provide a reliable and computationally efficient method for studying relativistic effects in late p-block elements.
• These potentials are valuable tools for advancing theoretical investigations in this area of chemistry.