Bonding in the helium dimer in strong magnetic fields: the role of spin and angular momentum

Abstract

We investigate the helium dimer in strong magnetic fields, focusing on the spectrum of low-lying electronic states and their dissociation curves, at the full configuration-interaction level of theory. To address the loss of cylindrical symmetry and angular momentum as a good quantum number for nontrivial angles between the bond axis and magnetic field, we introduce the almost quantized angular momentum (AQAM) and show that it provides useful information about states in arbitrary orientations. In general, strong magnetic fields dramatically rearrange the spectrum, with the orbital Zeeman effect bringing down states of higher angular momentum below the states with pure $\sigma$ character as the field strength increases. In addition, the spin Zeeman effect pushes triplet states below the lowest singlet; in particular, a field of one atomic unit is strong enough to push a quintet state below the triplets. In general, the angle between the bond axis and the magnetic field also continuously modulates the degree of $\sigma$, $\pi$, and $\delta$ character of bonds and the previously identified perpendicular paramagnetic bonding mechanism is found to be common among excited states. Electronic states with preferred skew field orientations are identified and rationalized in terms of permanent and induced electronic currents.

References in corpus (3)

• The $H{e}_2^{2+}$ molecular ion can exist in a magnetic field
• The carbon atom in intense magnetic fields
• The $He{H}^{+}$ molecular ion in a magnetic field

Cited by in corpus (5)

• Ab-Initio Molecular Dynamics with Screened Lorentz Forces. Part I. Calculation and Atomic Charge Interpretation of Berry Curvature
• Ab-Initio Molecular Dynamics with Screened Lorentz Forces. Part II. Efficient Propagators and Rovibrational Spectra in Strong Magnetic Fields
• Analytic Calculation of the Berry Curvature and Diagonal Born-Oppenheimer Correction for Molecular Systems in Uniform Magnetic Fields
• Magnetic-Translational Sum Rule and Approximate Models of the Molecular Berry Curvature
• Molecular vibrations in the presence of velocity-dependent forces