Intersite Coulomb Interactions in Charge-Ordered Systems.

Area of Science:

• Condensed Matter Physics
• Materials Science
• Computational Physics

Background:

• Ba_{1-x}K_{x}AO_{3} (A=Bi, Sb) are paradigmatic charge-ordered materials.
• Understanding their complex phase behavior requires advanced theoretical models.

Purpose of the Study:

• To investigate the role of extended Hubbard interactions coupled to phonons in Ba_{1-x}K_{x}AO_{3}.
• To establish a minimal theoretical criterion for describing spontaneous charge orders.

Main Methods:

• Utilizing ab initio approaches.
• Incorporating extended Hubbard interactions and electron-phonon coupling.
• Self-consistently calculating nearest-neighbor Hubbard interactions.

Main Results:

• The intersite Coulomb interaction significantly influences the distinct phases of these materials.
• Experimental features, including breathing instabilities and anomalous phonon dispersions, are well-reproduced.
• The transition between charge-density wave and superconducting states is explained.

Conclusions:

• A minimal criterion including self-consistently obtained nearest-neighbor Hubbard interactions is established for reliable charge order descriptions.
• This approach provides a robust framework for understanding complex electronic phases in solids.