He 2++ molecular ion in a strong time-dependent magnetic field: a current-density functional study

Area of Science:

• Quantum Chemistry
• Theoretical Physics
• Computational Materials Science

Background:

• Understanding molecular ion behavior under extreme conditions is crucial for advanced materials and plasma physics.
• Traditional time-dependent density functional theory (TD-DFT) often simplifies interactions, potentially limiting accuracy for dynamic systems.
• The He2++ molecular ion serves as a fundamental system for probing electronic responses to external fields.

Purpose of the Study:

• To investigate the time-dependent (TD) behavior of the He2++ molecular ion under strong, ultrashort magnetic fields.
• To compare the accuracy of a quantum fluid dynamics (QFD) and current-density functional theory (CDFT) approach against conventional TD-DFT.
• To elucidate the role of current-density dependent potentials in describing electron dynamics.

Main Methods:

• Employed a quantum fluid dynamics (QFD) and current-density functional theory (CDFT) framework.
• Utilized vector exchange-correlation (XC) potentials and energy density functionals dependent on both charge and current densities.
• Performed TD-QFD-CDFT computations with magnetic fields up to 10(11) G and compared results with conventional TD-DFT.

Main Results:

• The CDFT-based approach yielded significantly different TD exchange-correlation energy and electronic charge-density compared to conventional TD-DFT.
• These discrepancies were particularly pronounced at typical magnetic field strengths and during the time evolution of the field.
• The current-density dependent vector XC potential in CDFT was identified as the cause, inducing nonadiabatic effects and charge-density retardation.

Conclusions:

• Current-density functional theory offers a more nuanced description of He2++ dynamics under strong magnetic fields than conventional TD-DFT.
• The CDFT approach captures nonadiabatic effects and dissipative electron dynamics, treating electronic charge density as a quantum fluid.
• This study highlights the importance of including current-density effects for accurate modeling of molecular systems in intense time-dependent fields.