Correlating the antisymmetrized geminal power wave function

Area of Science:

• Quantum chemistry
• Condensed matter physics

Background:

• Superconductivity arises from strong pairing correlations, leading to off-diagonal long-range order in the two-particle density matrix.
• The antisymmetrized geminal power (AGP) wave function is a foundational model for qualitatively describing these correlations while preserving number symmetry.

Purpose of the Study:

• To investigate the utility of the AGP wave function as a reference state.
• To explore advanced quantum correlation techniques building upon the AGP.

Main Methods:

• Utilizing the antisymmetrized geminal power (AGP) as a reference state.
• Considering advanced correlation techniques: configuration interaction, coupled cluster theory, and random phase approximation.

Main Results:

• The AGP wave function, while simple, has limitations in quantitative accuracy across all correlation regimes.
• The AGP can serve as a valuable starting point for more sophisticated theoretical treatments of electron correlation.

Conclusions:

• The AGP wave function provides a qualitative yet limited description of pairing correlations.
• Employing the AGP as a reference state enables the application of advanced methods for quantitatively accurate correlation descriptions.