Magnetic-Field Density-Functional Theory (BDFT): Lessons from the Adiabatic Connection

Area of Science:

• Computational Physics
• Quantum Chemistry
• Materials Science

Background:

• Density-functional theory (DFT) is a powerful tool for electronic structure calculations.
• Studying magnetic phenomena computationally often requires advanced theoretical frameworks.
• Current-density functional theory (CDFT) has limitations in describing magnetic fields.

Purpose of the Study:

• To introduce and validate magnetic field density-functional theory (BDFT) as an alternative to CDFT.
• To clarify the relationship between BDFT and CDFT using convex analysis.
• To investigate the factors determining magnetizability and the role of electron density.

Main Methods:

• Development of the BDFT framework.
• Decomposition of energy into Kohn-Sham components.
• Analysis using convex analysis and saddle functions.
• Calculation of adiabatic-connection (AC) curves at varying field strengths and geometries.

Main Results:

• BDFT is a viable alternative to CDFT for magnetic phenomena.
• Magnetizability is primarily dependent on electron density components.
• Improvements in density approximations are more impactful for magnetizability than magnetic-field dependent correlation functionals.
• High accuracy requires including magnetic-field dependence once accurate charge density is achieved.
• Adiabatic-connection curves show similarity at different field strengths when calculated at field-specific equilibrium geometries.

Conclusions:

• BDFT provides a robust framework for magnetic phenomena within DFT.
• The accuracy of magnetizability calculations is strongly linked to the quality of the electron density.
• Existing DFT approximations may be applicable to systems in strong fields with careful consideration of static correlation.