Eur. Phys. J. D (2012) 66: 5
https://doi.org/10.1140/epjd/e2011-20550-0

Regular Article

Current-density functional theory study of the H₂ molecule evolving under a strong ultrashort magnetic field

Quantum Chemistry Group, Department of Chemistry & Centre of Advanced Studies in Chemistry, Panjab University, 160014 Chandigrah, India

^a e-mail: qlabspu@pu.ac.in

Received: 22 September 2011
Published online: 11 January 2012

Abstract

Hydrogen molecule in a strong ultrashort magnetic field is investigated through a current-density functional theory (CDFT) and quantum fluid dynamics (QFD) based approach employing current-density dependent vector exchange-correlation potential and energy density functional derived with a vorticity variable. The numerical computations through the CDFT based approach are performed for the H₂ molecule, starting initially from its field-free ground state, in a parallel internuclear axis and magnetic field-axis configuration with the internuclear separation R ranging from 0.1 a.u. to 14.0 a.u., and the strength of the time-dependent (TD) magnetic field varying between 0−10¹¹   G over a few femtoseconds. The numerical results are compared with that obtained using an approach based on the current-density independent approximation under similar computational constraints but employing only scalar exchange-correlation potential dependent on the electronic charge-density alone. The current-density based approach yields exchange- and correlation energy as well as electronic charge-density of the H₂ molecule drastically different from that obtained using current-independent approach, in particular, at TD magnetic field-strengths >10⁹ G during a typical time-period of the field when the magnetic-field had attained maximum applied field-strength and is switched to a decreasing ramp function. This nonadiabatic behavior of the TD electronic charge-density is traced to the TD vorticity-dependent vector exchange-correlation potential of the CDFT based approach. The interesting electron dynamics of the H₂ molecule in strong TD magnetic field is further elucidated by treating electronic charge-density as an ‘electron-fluid’. The present work also reveals interesting real-time dynamics on the attosecond time-scale in the electronic charge-density distribution of the hydrogen molecule.