Corrected small basis set Hartree-Fock method for large systems.

Area of Science:

• Quantum chemistry
• Computational chemistry
• Molecular modeling

Background:

• Accurate computation of large molecular systems is computationally demanding.
• Existing methods like DFT can suffer from self-interaction errors.
• Need for efficient methods to study structures and noncovalent interactions in large systems.

Purpose of the Study:

• To present a new quantum chemical method, Hartree-Fock-3c (HF-3c).
• To enable accurate calculations of structures, vibrational frequencies, and noncovalent interaction energies in large molecular systems.
• To offer a computationally efficient alternative to DFT and semiempirical methods.

Main Methods:

• Utilizes Hartree-Fock (HF) calculations with a small Gaussian atomic orbital (AO) basis set.
• Incorporates three physically motivated atom pair-wise correction terms: D3 for London dispersion, gCP for basis set superposition error, and short-ranged corrections for basis set incompleteness.
• Employs a total of nine global empirical parameters.

Main Results:

• HF-3c method tested on geometries of small organic molecules, interaction energies, and geometries of noncovalently bound complexes.
• Evaluated on supramolecular systems and protein structures.
• Achieved results comparable to large basis set DFT quality for most realistic test cases.

Conclusions:

• The HF-3c method provides a significant reduction in computational cost.
• It offers a viable and accurate approach for studying large molecular systems, including proteins.
• HF-3c is a promising tool for computational chemistry, especially when self-interaction errors are a concern.