Study of Sterically Crowded Alkanes: Assessment of Non-Empirical Density Functionals Including Double-Hybrid...

Area of Science:

• Computational chemistry
• Quantum chemistry
• Theoretical chemistry

Background:

• Sterically crowded alkanes present unique challenges in theoretical studies due to their complex electronic structures.
• Understanding their dissociation reactions is crucial for various chemical applications.

Purpose of the Study:

• To theoretically investigate the homolytic dissociation reactions of sterically crowded alkanes.
• To evaluate the performance of different parameter-free functionals, including hybrid and double-hybrid models.
• To assess the impact of dispersion corrections and tailored basis sets on accuracy and computational cost.

Main Methods:

• Employed a range of parameter-free functionals (semi-local, hybrid, double-hybrid).
• Included dispersion corrections (D4, NL) and a tailored basis set (DH-SVPD).
• Studied homolytic dissociation of alkanes with tert-butyl, adamantyl, and [1.1.1]propellanyl substituents.
• Analyzed interactions between tert-butyl molecules in repulsive and attractive regions.

Main Results:

• PBE-QIDH/DH-SVPD and r2SCAN-QIDH/DH-SVPD methods demonstrated an excellent balance between accuracy and computational cost.
• These methods provided relatively low errors compared to other quantum-chemical approaches.
• The DH-SVPD basis set showed effectiveness for non-covalent interactions in crowded systems.

Conclusions:

• The PBE-QIDH/DH-SVPD and r2SCAN-QIDH/DH-SVPD methods are highly competitive for studying sterically crowded alkanes.
• These computational approaches offer a cost-effective alternative for accurate theoretical investigations.
• The findings provide valuable insights into the dissociation mechanisms of complex alkane systems.