Self-consistent Kohn-Sham method based on the adiabatic-connection fluctuation-dissipation theorem and the...

Area of Science:

• Quantum Chemistry
• Computational Physics
• Materials Science

Background:

• The adiabatic-connection fluctuation-dissipation (ACFD) theorem is a powerful tool for developing accurate electronic structure methods.
• Direct random phase approximation (dRPA) methods, while useful, suffer from self-correlation errors and inaccuracies in describing one-electron systems.
• Exact exchange (EXX) methods offer a way to improve upon dRPA by incorporating the exact exchange kernel.

Purpose of the Study:

• To present a self-consistent Kohn-Sham method based on the ACFD theorem using the frequency-dependent exact exchange kernel (EXX-ACFD).
• To evaluate the accuracy of the SC-EXX-ACFD method for various chemical and physical systems, comparing it to existing methods.
• To assess the computational cost and scalability of the SC-EXX-ACFD method.

Main Methods:

• Development and implementation of a self-consistent Kohn-Sham method incorporating the exact exchange kernel within the ACFD framework (SC-EXX-ACFD).
• Calculation of reaction energies for small molecules with high-accuracy experimental data.
• Evaluation of non-covalently bonded dimers (S22 set) and potential energy curves for noble gas, water, and benzene dimers.
• Comparison with established quantum chemistry methods (MP2, CCSD, CCSD(T)) and other ACFD variants.

Main Results:

• The SC-EXX-ACFD method yields more accurate correlation potentials than dRPA, correctly describing one-electron systems without self-correlation errors.
• Self-consistent evaluation of EXX-ACFD total energies significantly improves accuracy compared to non-self-consistent calculations.
• Calculated reaction energies and interaction energies for dimers show high accuracy, competitive with or superior to high-level wavefunction methods.
• The computational scaling remains N(5), similar to non-self-consistent methods, but with a larger prefactor.

Conclusions:

• The SC-EXX-ACFD method provides a significant advancement in electronic structure calculations, offering improved accuracy and reliability.
• This method is particularly effective for systems with static correlation and serves as a competitive alternative to traditional high-level methods for larger systems.
• The SC-EXX-ACFD approach represents a promising direction for accurate and efficient quantum chemical calculations.