Communication: the description of strong correlation within self-consistent Green's function second-order...

Area of Science:

• Computational Chemistry
• Condensed Matter Physics
• Quantum Many-Body Theory

Background:

• Strong electron correlation poses significant challenges for traditional electronic structure methods.
• Accurate modeling of materials exhibiting strong correlation is crucial for understanding phenomena like metal-insulator transitions.

Purpose of the Study:

• To implement and validate a self-consistent Green's function many-body theory within a second-order approximation (GF2) for molecular systems.
• To assess the capability of the GF2 method in describing systems with strong electronic correlation.

Main Methods:

• Iterative solution of the Dyson equation in an atomic orbital basis.
• Utilizing imaginary frequency and imaginary time domains for Green's function and self-energy.
• Employing fast Fourier transforms for efficient data transformation.

Main Results:

• The GF2 method was applied to archetypal examples of strong correlation, including a H32 lattice with a multireference ground state.
• The GF2 approach successfully described metal-to-insulator transitions in these systems.
• The method provided physically meaningful results without requiring spin-symmetry breaking.

Conclusions:

• Self-consistent Green's function many-body theory (GF2) is a viable computational approach for studying strong correlation effects.
• The GF2 method offers a computationally tractable single-particle formalism for complex electronic systems.
• This implementation enables accurate descriptions of challenging electronic phenomena in molecular systems.