Relativistic Polarizable Embedding.

Area of Science:

• Computational chemistry
• Quantum chemistry
• Relativistic effects

Background:

• Environmental effects significantly influence chemical reactions, especially those involving relativistic effects.
• Progress in nonrelativistic quantum chemistry has enabled environment inclusion, necessitating similar advancements in relativistic calculations.
• The polarizable embedding (PE) model offers an efficient way to incorporate environmental electrostatic effects.

Purpose of the Study:

• To extend environmental inclusion capabilities to relativistic quantum chemistry.
• To present the theory and implementation of four- and exact two-component Hamiltonians within the PE framework (PE-4c-DFT and PE-X2C-DFT).
• To develop and apply time-dependent (TD) versions for calculating excitation energies.

Main Methods:

• Implementation of four- and exact two-component Hamiltonians within the polarizable embedding (PE) framework.
• Development of linear response formalism for time-dependent (TD) properties (PE-TD-4c-DFT and PE-TD-X2C-DFT).
• Calculation of excitation energies for TcO4- and ReO4- ions in water using PE-TD-4c-PBE0.

Main Results:

• The study successfully implemented PE-4c-DFT and PE-X2C-DFT models for relativistic quantum chemistry with environmental effects.
• Calculated excitation energies for TcO4- and ReO4- ions in water.
• Quantified the relative contributions of relativistic effects and solvent effects (direct and indirect) to excitation energy shifts.

Conclusions:

• Both relativistic effects and solvent interactions significantly shift excitation energies.
• The extent of these shifts varies depending on the specific ion and electronic transition.
• The developed models provide a robust framework for studying environmentally-influenced chemistry where relativistic effects are crucial.