Linearized Jastrow-style fluctuations on spin-projected Hartree-Fock

Area of Science:

• Computational Chemistry
• Electronic Structure Theory
• Quantum Many-Body Physics

Background:

• Accurate and efficient description of strong electronic correlations is a key challenge in electronic structure theory.
• Projected Hartree-Fock (PHF) theory shows promise but suffers from lack of size consistency and extensivity.
• These issues lead to vanishing correlation energy in the thermodynamic limit and incorrect dissociation energies.

Purpose of the Study:

• To address the limitations of size consistency and extensivity in Projected Hartree-Fock theory.
• To develop an improved theoretical framework for describing electronic correlations in molecules and materials.
• To extend a recently proposed Jastrow-type correlator method to PHF theory.

Main Methods:

• Applied a Jastrow-type correlator, inspired by Neuscamman's work, within the Projected Hartree-Fock framework.
• Linearized the correlator for computational efficiency.
• Extended the method to incorporate spin fluctuations and tested on the Hubbard Hamiltonian and molecular systems.

Main Results:

• The proposed method aims to rectify the lack of size consistency in PHF theory.
• Incorporation of spin fluctuations enhances the description of electronic correlations.
• Demonstrated applicability to the Hubbard model and simple molecular systems.

Conclusions:

• The developed approach offers a potential solution to the size consistency and extensivity problems in PHF theory.
• This advancement is crucial for accurate electronic structure calculations, particularly for systems with strong correlations.
• Further studies are warranted to explore the full capabilities of this method in various chemical and physical systems.