Molecular-Orbital Basis for Superconductivity in High- and Low-Dimensional Metals.
Abstract
A real-space molecular-orbital description of electronic wave functions which are postulated to be the precursors of the superconducting state in high- and low-dimensional metals is presented, based on self-consistent X-alpha scattered-wave (SCF-X alpha-SW) molecular-orbital calculations for clusters representing the local molecular environments in these materials. It is shown that there is a persistent correlation between the occurrence of superconductivity in a material and the existence of spatially delocalized molecular orbitals at the Fermi energy which are bonding within and antibonding between 'layers' or 'tubes' of overlapping atomic orbitals that span many atoms, forming a type of 'electron network' at the Fermi energy, as exemplified by P pi 'layered' molecular-orbital topologies in Al and (TMTSF)2PF6, and by d sigma 'tabular' molecular-orbital topologies in Nb and Nb3Sn. This description of the precursor superconducting state is consistent with the original conjectures of London that the superconducting-state wave function is 'molecular' in nature, 'rigid' in character, and of wide spatial extent, from which observed physical properties (e.g., diamagnetism and nondissipative electrical currents) of the superconducting state logically follow.
Document Details
- Document Type
- Technical Report
- Publication Date
- Sep 24, 1982
- Accession Number
- ADA119784
Entities
People
- Keith H. Johnson
- R. P. Messmer
Organizations
- Massachusetts Institute of Technology