Extending conceptual DFT to include external variables: the influence of magnetic fields

Area of Science:

• Theoretical Chemistry
• Quantum Chemistry
• Chemical Physics

Background:

• Conceptual Density Functional Theory (DFT) describes chemical reactivity using descriptors like electronic chemical potential and hardness.
• Understanding atomic properties under varying reaction conditions, including external fields, is crucial for predicting chemical behavior.
• The influence of magnetic fields on atomic electronic structure and reactivity is not fully understood.

Purpose of the Study:

• To extend conceptual DFT to incorporate the effects of external magnetic fields on atomic properties.
• To investigate the behavior of global reactivity descriptors (chemical potential and hardness) for main group atoms (H-Kr) under varying magnetic field strengths.
• To analyze the impact of magnetic fields on atomic electronic configurations and their periodicity.

Main Methods:

• Utilized current density-functional theory (DFT) to model main group atoms.
• Varied magnetic field strength (|B|) from 0.0 to 1.0 B₀ (≈ 2.3505 × 10⁵ T), covering Coulomb and intermediate regimes.
• Calculated ionization energy (I) and electron affinity (A) to determine electronegativity (χ) and hardness (η).

Main Results:

• Observed piecewise behavior of I and A, leading to complex variations in χ and η with increasing magnetic field strength.
• In the Coulomb regime (|B| ≈ 0), familiar atomic periodicity was maintained.
• In the intermediate regime, magnetic fields induced configurational changes, causing discontinuous shifts in atomic properties and altering periodic trends.

Conclusions:

• External magnetic fields significantly modify atomic properties and their periodicity, fundamentally altering chemical behavior.
• Periodic tables of electronegativity and hardness at |B| = 0.5 B₀ show distinct trends, with elements in groups 1-2 increasing and groups 16-18 decreasing.
• These findings provide a basis for predicting chemical reactivity under extreme magnetic field conditions.