Chalcogen bonds: Hierarchical ab initio benchmark and density functional theory performance study.

Area of Science:

• Computational Chemistry
• Quantum Chemistry
• Chemical Physics

Background:

• Chalcogen bonds are crucial non-covalent interactions.
• Accurate theoretical methods are needed to study D2 Ch•••A- chalcogen bonds.
• Relativistic effects are important for these systems.

Purpose of the Study:

• To perform a hierarchical ab initio benchmark of relativistic quantum chemical methods.
• To evaluate the performance of various ZORA-relativistic Density Functional Theory (DFT) functionals.
• To identify accurate and efficient methods for studying D2 Ch•••A- chalcogen bonds.

Main Methods:

• Hierarchical ab initio calculations using ZORA-relativistic methods (HF, MP2, CCSD, CCSD(T)).
• Utilized Karlsruhe basis sets (ZORA-def2-SVP, ZORA-def2-TZVPP, ZORA-def2-QZVPP) with and without diffuse functions.
• Assessed 13 ZORA-relativistic DFT approaches with the Slater-type QZ4P basis set, using benchmark results as reference.

Main Results:

• Highest-level ab initio complexation energies (ΔE_CPC) converged within 1.1-3.4 kcal/mol.
• M06-2X, B3LYP, and M06 functionals demonstrated the best performance among DFT methods.
• These top functionals yielded mean absolute errors (MAE) of 4.1, 4.2, and 4.3 kcal/mol, respectively.

Conclusions:

• ZORA-relativistic DFT methods, particularly M06-2X, B3LYP, and M06, are suitable for studying D2 Ch•••A- chalcogen bonds.
• The chosen ab initio methods provide reliable benchmark data for DFT performance evaluation.
• This work offers guidance for selecting accurate computational methods in chalcogen bond research.