A semiempirical long-range corrected exchange correlation functional including a short-range Gaussian attenuation...

Area of Science:

• Computational Chemistry
• Quantum Chemistry
• Materials Science

Background:

• Density Functional Theory (DFT) is a cornerstone of modern computational chemistry.
• Accurate prediction of molecular properties, including ground and excited states, is crucial for chemical research.
• Existing DFT functionals often struggle to balance accuracy for both ground and excited-state properties.

Purpose of the Study:

• To develop and validate an improved long-range corrected (LC) density functional.
• To enhance the Becke97 (B97) exchange-correlation functional with a short-range Gaussian attenuation (LCgau).
• To assess the performance of the new LCgau-B97 functional across a range of molecular properties.

Main Methods:

• Application of an improved long-range correction scheme (LCgau) to the B97 functional.
• Optimization of linear parameters using least squares fitting.
• Tuning of the μ parameter for long-range Hartree-Fock (HF) exchange and short-range Gaussian parameters for HF exchange inclusion.

Main Results:

• The LCgau-B97 functional demonstrated high performance for both ground and excited state properties.
• LCgau-B97 outperformed other tested semiempirical DFT functionals (e.g., ωB97, BMK, M0x-family).
• Optimal μ values varied for different excitation types: small μ (∼0.2) for local and charge-transfer excitations, larger μ (0.42) for Rydberg excitations.

Conclusions:

• The LCgau-B97 functional offers a significant improvement for predicting molecular properties.
• This method provides a balanced and accurate approach for both ground and excited-state calculations.
• The findings highlight the importance of parameter optimization for specific electronic excitation types in DFT.