A Paramagnetic Bonding Mechanism for Diatomics in Strong Magnetic Fields

• Published in: Science (American Association for the Advancement of Science) Vol. 337; no. 6092; pp. 327 - 331
• Main Authors: Lange, Kai K., Tellgren, E. I., Hoffmann, M. R., Helgaker, T.
• Format: Journal Article
• Language: English
• Published: Washington, DC American Association for the Advancement of Science 20.07.2012; The American Association for the Advancement of Science
• Subjects: Atomic and molecular physics; Atomic energy levels; Atoms; Calculations and mathematical techniques in atomic and molecular physics (excluding electron correlation calculations); Chemical bonding; Chemistry; Electronic structure of atoms, molecules and their ions: theory; Electrons; Energy; Exact sciences and technology; Magnetic field strength; Magnetic fields; Molecular properties and interactions with photons; Molecules; Optical activity and dichroism; magnetooptical and electrooptical spectra; Orbitals; Organic Chemistry; Other magnetooptical and electrooptical effects; Parallel lines; Physics; Potential energy curve; Hartree-Fock calculations; Electron pairs; Inorganic compounds; Hydrogen Molecules; Magnetic field effects; Singlet state; Diatomic molecules; Bond lengths; Triplet state; High field; Valence electron; Chemical bonds; Binding mode; Basis set superposition error; Helium Molecules
• ISSN: 0036-8075; 1095-9203
• DOI: 10.1126/science.1219703

Elementary chemistry distinguishes two kinds of strong bonds between atoms in molecules: the covalent bond, where bonding arises from valence electron pairs shared between neighboring atoms, and the ionic bond, where transfer of electrons from one atom to another leads to Coulombic attraction between the resulting ions. We present a third, distinct bonding mechanism: perpendicular paramagnetic bonding, generated by the stabilization of antibonding orbitals in their perpendicular orientation relative to an external magnetic field. In strong fields such as those present in the atmospheres of white dwarfs (on the order of 10 5 teslas) and other stellar objects, our calculations suggest that this mechanism underlies the strong bonding of H 2 in the $^ 3\sum \display _{u} ^{+} (1 \sigma _g 1 \sigma _{u} ^{*})$ triplet state and of He 2 in the $^ 1\sum \display _{g} ^{+} (1 \sigma _{g} ^{2} 1 \sigma _{u} ^{*2} )$ singlet state, as well as their preferred perpendicular orientation in the external field.