Variational study of the interacting, spinless Su-Schrieffer-Heeger model

Area of Science:

• Condensed Matter Physics
• Quantum Materials
• Solid State Theory

Background:

• The Su-Schrieffer-Heeger (SSH) model describes 1D materials with alternating bonds.
• Understanding its phase diagram and polarization is crucial for novel electronic properties.
• Nearest neighbor interactions and alternating hopping are key parameters influencing material behavior.

Purpose of the Study:

• To investigate the phase diagram and total polarization distribution of the 1D SSH model.
• To analyze the impact of nearest neighbor interactions on electronic transitions.
• To explore how correlations affect chiral symmetry and polarization behavior.

Main Methods:

• Extended Baeriswyl variational wave function to incorporate alternating hopping parameters.
• Comparison of variational wave function energies with exact diagonalization results.
• Calculation of gauge-invariant cumulants (Zak phase) to reconstruct polarization distribution.

Main Results:

• Identified a conductor-to-insulator transition at a lower interaction strength than previously known.
• The phase diagram exhibits similarities to the Kane-Mele-Hubbard model.
• Polarization changes discontinuously when crossing a metallic phase line, but smoothly through insulating states.

Conclusions:

• Electron correlations in the SSH model can break chiral symmetry, analogous to adding a Rice-Mele potential.
• The method provides a robust way to study polarization and phase transitions in 1D systems.
• Findings offer insights into topological phase transitions and symmetry breaking in correlated electron systems.