λ-Density Functional Valence Bond: A Valence Bond-Based Multiconfigurational Density Functional Theory With a Single...

Area of Science:

• Computational chemistry
• Quantum chemistry

Background:

• Accurate theoretical methods are crucial for understanding molecular systems, especially those with strong electron correlation.
• Existing methods like Kohn-Sham density functional theory (KS-DFT) and valence bond (VB) theory have limitations in describing complex electronic structures.

Purpose of the Study:

• To introduce a novel hybrid multireference density functional theory (MRDFT) method named λ-DFVB.
• To enhance the description of electron correlation in molecular systems using a variable hybrid parameter.

Main Methods:

• The λ-DFVB method combines valence bond self-consistent field (VBSCF) with Kohn-Sham density functional theory (KS-DFT).
• It utilizes a variable hybrid parameter (λ) dependent on the system's multireference character.
• Incorporates leading determinant correlation energy (E_C) for size consistency at dissociation limits.

Main Results:

• Test calculations demonstrate satisfactory performance for potential energy surfaces and bond dissociation energies.
• The method accurately predicts reaction barriers and singlet-triplet energy gaps.
• λ-DFVB shows potential for accurately modeling molecular systems with strong correlation.

Conclusions:

• The developed λ-DFVB method offers a promising approach for studying strongly correlated molecular systems.
• Its variable parameterization and size consistency ensure reliable results across various chemical phenomena.
• This method advances the capabilities of multireference density functional theory.