Structural relaxation due to electronic correlations in the paramagnetic insulator KCuF3

Area of Science:

• Condensed Matter Physics
• Computational Materials Science
• Quantum Chemistry

Background:

• Strongly correlated electron systems present significant challenges for accurate theoretical modeling.
• Understanding electronic correlations is crucial for predicting material properties, including structural stability.
• Existing computational methods often struggle to incorporate both electronic correlations and atomic displacements simultaneously.

Purpose of the Study:

• To develop a novel computational scheme capable of treating atomic displacements and structural relaxation driven by electronic correlations.
• To integrate ab initio band structure calculations with dynamical mean-field theory (DMFT) for a more comprehensive material investigation.
• To validate the new method by comparing its predictions with experimental data for a known correlated material.

Main Methods:

• Formulation of a computational scheme combining ab initio band structure calculations with dynamical mean-field theory.
• Implementation using a plane-wave pseudopotential framework.
• Application to investigate the Jahn-Teller distortion and orbital ordering in KCuF3.

Main Results:

• The developed scheme successfully accounts for atomic displacements arising from electronic correlations.
• Calculations for paramagnetic KCuF3 revealed the equilibrium Jahn-Teller distortion.
• The predicted antiferro-orbital order for KCuF3 showed excellent agreement with experimental observations.

Conclusions:

• The integrated computational approach provides a robust framework for studying complex materials with strong electron-electron interactions.
• The method's ability to capture coupled electronic and structural phenomena is demonstrated by its success in modeling KCuF3.
• This work offers a promising avenue for advancing the theoretical understanding and prediction of properties in correlated materials.