Long-range-corrected multiconfiguration density functional with the on-top pair density

Area of Science:

• Quantum Chemistry
• Computational Materials Science

Background:

• Accurate modeling of electron correlation is crucial for predicting molecular properties.
• Existing density functional approximations often struggle with dynamic correlation effects.

Purpose of the Study:

• To develop a novel multiconfiguration density functional (lrAC0-postCAS) that combines short-range density functional approximation with long-range correlation correction.
• To assess the performance of lrAC0-postCAS for calculating dissociation and excitation energies.

Main Methods:

• The method employs a short-range density functional approximation and a new long-range correction derived from adiabatic connection formalism.
• It utilizes wavefunctions of the complete active space (CAS) type.
• The functional incorporates on-top pair density via auxiliary spin densities to mitigate self-interaction and static correlation errors.

Main Results:

• The non-self-consistent variant, lrAC0-postCAS, was studied.
• Numerical results for dissociation and excitation energies demonstrate high accuracy.
• The method achieves accuracy comparable to computationally intensive ab initio methods.

Conclusions:

• lrAC0-postCAS offers a computationally efficient yet accurate approach for describing dynamic correlation.
• The developed functional shows promise for accurate predictions in quantum chemistry and materials science.