Correlation-driven phenomena in periodic molecular systems from variational two-electron reduced density matrix...

Area of Science:

• Computational chemistry
• Condensed matter physics
• Quantum mechanics

Background:

• Periodic molecular systems are computationally challenging due to their infinite nature and strong electron correlation.
• Accurate prediction of correlation-driven phenomena is crucial for understanding material properties.

Purpose of the Study:

• To generalize variational two-electron reduced density matrix (2-RDM) theory for strongly correlated periodic systems.
• To compute energies and properties of these challenging systems.

Main Methods:

• Direct computation of the unit-cell 2-RDM under N-representability conditions.
• Application to canonical systems: periodic metallic hydrogen chains and periodic acenes.
• Comparison with non-periodic calculations to highlight the impact of periodic boundary conditions.

Main Results:

• The periodic variational 2-RDM theory successfully predicts the Mott metal-to-insulator transition in hydrogen chains.
• It also captures length-dependent polyradical formation in acenes, phenomena missed by single-reference theories.
• Periodic calculations reveal significant changes in energies and increased electron correlation compared to non-periodic approaches.

Conclusions:

• The generalized 2-RDM theory provides a robust framework for studying strongly correlated periodic systems.
• This methodology enables larger active spaces, advancing the study of correlation-driven phenomena in molecular solids and materials.