Comparing first-principles density functionals plus corrections for the lattice dynamics of YBa2Cu3O6

Area of Science:

• Condensed Matter Physics
• Materials Science
• Computational Chemistry

Background:

• The mechanism of unconventional high-temperature superconductivity in cuprates is not fully understood.
• Accurate theoretical descriptions of lattice dynamics are essential for advancing this understanding.
• Previous first-principles calculations have lacked sufficient accuracy for cuprate lattice dynamics.

Purpose of the Study:

• To compare the performance of different density functional approximations for calculating lattice dynamics in YBa2Cu3O6.
• To investigate the impact of van der Waals (vdW) and on-site Hubbard U corrections on phonon spectra.
• To elucidate the role of self-interaction and vdW effects in accurate first-principles calculations for cuprates.

Main Methods:

• Utilizing the r2SCAN meta-generalized gradient approximation (meta-GGA) functional.
• Comparing Perdew-Burke-Ernzerhof (PBE) and r2SCAN functionals.
• Incorporating corrections such as on-site Hubbard U and D4 van der Waals (vdW) methods.
• Analyzing phonon spectra and magnetoelastic coupling in YBa2Cu3O6.

Main Results:

• r2SCAN accurately predicts phonon spectra for YBa2Cu3O6, revealing significant magnetoelastic coupling.
• Van der Waals and self-interaction corrections are critical for accurate first-principles lattice dynamics.
• The good performance of r2SCAN is partly attributed to its inherent partial inclusion of these effects.
• Tao-Mo series meta-GGAs were also evaluated and compared.

Conclusions:

• Accurate lattice dynamics calculations for cuprates require careful consideration of vdW and self-interaction corrections.
• The r2SCAN functional offers a more accurate approach for studying lattice dynamics in materials like YBa2Cu3O6.
• This work advances both materials science understanding and density functional theory development.