Density Matrix Embedding: A Strong-Coupling Quantum Embedding Theory.

Area of Science:

• Quantum Chemistry
• Computational Physics
• Materials Science

Background:

• Traditional embedding methods struggle with strongly correlated quantum systems.
• Handling open quantum systems and strong environmental coupling presents significant challenges.
• Existing techniques often rely on empirical approximations for strong interactions.

Purpose of the Study:

• To extend Density Matrix Embedding Theory (DMET) beyond lattice models to the full chemical Hamiltonian.
• To develop a rigorous quantum embedding method capable of treating arbitrary, strongly coupled fragments.
• To provide a robust alternative to empirical approaches for complex quantum systems.

Main Methods:

• Extension of DMET to incorporate the full chemical Hamiltonian.
• Development of a rigorous quantum bath to model fragment-environment entanglement.
• Application to strongly correlated hydrogen ring and grid models.

Main Results:

• DMET successfully models strongly correlated hydrogen models, including challenging ring and grid systems.
• The method accurately describes the symmetric dissociation of a 4x3 hydrogen atom grid.
• Effective treatment of fragments as small as single hydrogen atoms was demonstrated.

Conclusions:

• DMET provides a rigorous and accurate approach for embedding fragments in complex quantum systems.
• The extended DMET overcomes limitations of traditional embedding and quantum chemistry methods.
• This work enables new avenues for studying strongly coupled, strongly correlated systems fragment by fragment.