A DFT+nonhomogeneous DMFT approach for finite systems.

Area of Science:

• Computational Physics
• Materials Science
• Quantum Chemistry

Background:

• Accurately describing electron-electron correlation is crucial for understanding nanosystem properties.
• Standard Density Functional Theory (DFT) and DFT+U methods often struggle with electron correlation in nanosystems.
• Dynamical Mean-Field Theory (DMFT) offers a more robust approach but can be computationally intensive.

Purpose of the Study:

• To develop and validate a computationally efficient combined DFT+DMFT approach for nanosystems.
• To investigate the size-dependent magnetic properties of iron nanoparticles.
• To compare the accuracy of the new DFT+DMFT method against DFT and DFT+U.

Main Methods:

• Formulation of a combined density functional theory/nonhomogeneous dynamical mean-field theory (DFT+DMFT) framework.
• Implementation of an approximate iterated perturbation theory impurity solver within the DFT+DMFT approach.
• Application to iron nanoparticles ranging from 11 to 100 atoms to study magnetic properties.

Main Results:

• The DFT+DMFT approach provides reliable and efficient inclusion of electron-electron correlation effects.
• The method shows excellent agreement with experimental data for the magnetic properties of iron nanoparticles.
• DFT+DMFT accurately reproduces experimentally observed oscillations in magnetic moment with nanoparticle size.
• The new approach significantly outperforms standard DFT and DFT+U calculations in accuracy.

Conclusions:

• The developed DFT+DMFT method is suitable for accurate and realistic descriptions of nanosystems up to approximately 100 atoms.
• This approach offers a significant improvement over existing methods for modeling magnetic properties in iron nanoparticles.
• The findings pave the way for more precise theoretical investigations of electron correlation in nanomaterials.