Accession Number : ADA119784

Title :   Molecular-Orbital Basis for Superconductivity in High- and Low-Dimensional Metals.

Descriptive Note : Interim technical rept.,

Corporate Author : MASSACHUSETTS INST OF TECH CAMBRIDGE CENTER FOR MATERIALS SCIENCE AND ENGINEERING

Personal Author(s) : Johnson,K H ; Messmer,R P

PDF Url : ADA119784

Report Date : 24 Sep 1982

Pagination or Media Count : 102

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.

Descriptors :   *Metals, *Molecular orbitals, *Superconductors, Superconductivity, Electric current, Wave functions, Electromagnetic radiation, Atomic orbitals, Physical properties, Precursors, Energy transfer, Fermi surfaces, Bonding, Atoms, Crystallography, Crystal structure

Subject Categories : Metallurgy and Metallography
      Electricity and Magnetism
      Nuclear Physics & Elementary Particle Physics

Distribution Statement : APPROVED FOR PUBLIC RELEASE