Complex periodic patterns are generated by magnetic fields
Electronegativity and hardness of elements can change dramatically when exposed to intense magnetic fields, according to a new computer research. 1 Across chemistry and physics, the unique behaviour of chemical systems in this sort of environment has long been a focus of study. A approach known as conceptual density-functional theory (DFT) has now been expanded by Belgian and UK academics in order to investigate these theories further.
A subset of density functional theory, known as conceptual DFT, is devoted to the study of chemical concepts such as electronegativity and hardness. DFT has developed into a theory of reactivity that may help scientists understand and predict the reactivity of compounds, says Paul Geerlings, a professor of chemistry at the Free University of Brussels. In collaboration with Frank de Proft, Geerlings’ research has broadened the scope of conceptual DFT to incorporate electric fields and mechanical forces external to the system. 2,3 By extending the framework of conceptual DFT to accommodate them, de Proft explains, it was ‘natural’ to do so.
De Proft’s team of Geerlings and de Proft has now utilised conceptual DFT to compute ionisation energy and electron affinity in magnetic fields as high as 1B0 for the major group atoms from hydrogen to Krypton (235,000Tesla). They then estimated the electronegativity and hardness, allowing them to build an alternative periodic table that reveals patterns that are far from what would be anticipated if there were no external influences. Researchers from the Universities of Nottingham and Nottingham Trent University found that as the intensity of the magnetic field increased, the pattern of ionisation energies and electron affinities, and therefore electronegativity and hardness, became increasingly complex. The reason for this is because atoms respond to a magnetic field by changing their ground state structure, adding or removing electrons from various orbitals with differing energies. Still, “a periodic pattern in the change of electronegativity and hardness with regard to magnetic field intensity was readily apparent,” observes Geerlings.
Scientists are hopeful that their discoveries may help them forecast how magnetic fields affect chemical bonding behaviour. Nottingham team member Andrew Teale adds that, for example, differences in electronegativity of the hydrogen and fluorine atoms as a function of magnetic fields imply that at some threshold field strength, the polarity the link will reverse. Researchers found that the dipole moment does indeed shift direction as field intensity increases while running computations on this molecule. Even astronomical objects like white dwarf stars, which have field strengths on the scale of 1B0, might be subject to similar predictions. Speaking about the future of research in this field, Irons said: ‘It certainly will be an intriguing subject.’
Indian Institute of Technology Kharagpur’s Pratim Chattaraj warns that ‘one must be careful, as the electronegativity and hardness are respectively defined as both the first and the second derivatives of energy with respect to electrons at a constant external potential,’ according to an expert in DFT Defying definitions, you can change the external potential by changing the magnetic field intensity.’