The p-block challenge: assessing quantum chemistry methods for inorganic heterocycle dimerizations

Area of Science:

• Computational Chemistry
• Quantum Chemistry
• Materials Science

Background:

• P-block elements are crucial for applications like frustrated Lewis pairs and optoelectronics.
• High-quality benchmark data for theoretical descriptions of p-block elements are scarce.
• Accurate computational methods are needed to predict properties of p-block compounds.

Purpose of the Study:

• To present a comprehensive benchmark set (IHD302) of 604 dimerization energies for 302 inorganic benzenes.
• To provide high-accuracy reference data for evaluating approximate quantum chemical methods.
• To assess the performance of various density functional theory (DFT) and semi-empirical methods.

Main Methods:

• Generation of reference data using explicitly correlated local coupled cluster theory (PNO-LCCSD(T)-F12/cc-VTZ-PP-F12(corr.)) with basis set correction.
• Assessment of 26 DFT methods, 5 composite DFT approaches, and 5 semi-empirical methods.
• Utilized re-contracted basis sets and pseudopotentials for improved accuracy with 4th-period p-block elements.

Main Results:

• Identified top-performing DFT functionals for covalent dimerizations, including r2SCAN-D4, r2SCAN0-D4, ωB97M-V, and revDSD-PBEP86-D4.
• Observed significant errors in covalent dimerization energies for 4th-period elements using standard basis sets.
• Demonstrated substantial improvements for 4th-row elements with specialized pseudopotentials and basis sets.

Conclusions:

• The IHD302 set presents a significant challenge for current quantum chemical methods due to unique bonding characteristics.
• The developed computational protocol and benchmark set are valuable for advancing theoretical chemistry.
• This work facilitates the development of more robust and transferable approximate quantum chemical methods for p-block elements.