Predicting fundamental gaps accurately from density functional theory with non-empirical local range separation.

Area of Science:

• Quantum Chemistry
• Computational Materials Science
• Solid-State Physics

Background:

• Accurate prediction of electronic properties, particularly the fundamental gap, is essential for materials science.
• Existing density functional approximations often struggle with charge-transfer excitations and delocalized electronic systems.
• Self-interaction error remains a persistent challenge in standard approximations.

Purpose of the Study:

• To develop a novel exchange-correlation functional for improved electronic structure calculations.
• To address limitations in existing functionals, specifically self-interaction error and accuracy for challenging systems.
• To provide a reliable tool for spectroscopic applications and accurate prediction of fundamental gaps.

Main Methods:

• A range-separated density functional approach that splits Coulomb interaction into long- and short-range components.
• Non-empirical determination of the range separation parameter.
• Implementation within the generalized Kohn-Sham (GKS) theoretical framework.

Main Results:

• The proposed functional satisfies key physical constraints, including homogeneous and slowly varying density limits.
• It correctly reproduces the long-range potential and eliminates the one-electron self-interaction error.
• Demonstrated high accuracy in predicting fundamental gaps across diverse systems, including organic semiconductors.

Conclusions:

• The developed range-separated functional offers a significant improvement for calculating electronic properties.
• It provides a robust method for spectroscopic purposes and accurately predicts fundamental gaps.
• This approach shows particular promise for systems with complex electronic structures, such as organic semiconductors.