Ab Initio Electron-Phonon Interactions in Correlated Electron Systems.

Area of Science:

• Condensed matter physics
• Materials science
• Computational materials science

Background:

• Electron-phonon (e-ph) interactions are fundamental to many solid-state phenomena, including superconductivity and transport.
• Accurate first-principles calculations of e-ph interactions are crucial but challenging in correlated electron systems (CES).
• Standard density functional theory (DFT) often fails to describe the ground state of CES, limiting e-ph calculations.

Purpose of the Study:

• To establish a reliable first-principles approach for calculating e-ph interactions in CES.
• To address the limitations of standard DFT in describing CES properties.
• To enable quantitative studies of e-ph interactions and polaron effects in materials like transition metal oxides and Mott insulators.

Main Methods:

• Utilizing Hubbard-corrected density functional theory (DFT+U) and its linear response extension (DFPT+U).
• Applying the DFPT+U framework to calculate e-ph interactions and electron spectral functions.
• Investigating the prototypical Mott system, Cobalt Oxide (CoO).

Main Results:

• DFPT+U successfully removes unphysical divergences found in standard DFPT calculations for e-ph interactions.
• The method accurately captures the long-range Fröhlich interaction in CES.
• Demonstrated the ability to model polaron effects in a Mott insulator (CoO).

Conclusions:

• The developed DFPT+U approach provides a broadly applicable and affordable method for quantitative e-ph interaction studies in CES.
• This work offers a novel theoretical tool for interpreting experimental data in a wide range of correlated materials.
• Enables accurate modeling of electron-phonon coupling and its consequences in complex materials.