Microscopic response to inhomogeneous deformations in curvilinear coordinates

Area of Science:

• Condensed Matter Physics
• Materials Science
• Theoretical Physics

Background:

• Mechanical deformations in materials can be viewed as coordinate transformations.
• Electrostatics in deformable media requires covariance with these transformations, a concept from general relativity.
• Density-functional perturbation theory (DFPT) is a powerful tool for studying material properties.

Purpose of the Study:

• To incorporate general relativity-based covariance requirements into DFPT.
• To develop a method for calculating microscopic charge density and electrostatic potential responses to deformation.
• To derive general surface contributions to flexoelectricity in finite objects.

Main Methods:

• Generalized coordinate transformations for mechanical deformation.
• Integration of covariance principles into DFPT.
• Derivation of flexoelectric surface contributions.

Main Results:

• A novel DFPT framework for electrostatics in deformable media.
• General derivation of surface contributions to flexoelectric response.
• Demonstration of paradoxical surface charge behavior due to broken translational periodicity.

Conclusions:

• The new approach provides access to deformation-induced electrostatic responses.
• The study resolves controversies regarding flexoelectric surface effects.
• Non-trivial surface charges arise from the breakdown of periodicity.