Molecular Orbitals and Superconductivity.
Abstract
A real-space molecular-orbital description of electronic wavefunctions which are postulated to be the precursors of the superconducting state in metals, alloys, compounds, and noncrystalline materials is presented, based on self-consistent-field X-alpha scattered-wave molecular-orbital calculations for clusters representing the local molecular environments in these materials. It is shown through a variety of examples that there is a persistent correlation between the occurrence of superconductivity in a material and the existence of molecular orbitals at the Fermi energy with coherent (i.e., in-phase) spatially extended bonding atomic-orbital components. It is also argued that, while these individual molecular-orbital components are usually one-dimensional or two-dimensional in nature, the composite precursor superconducting state of a material arises from a coherent three-dimensional network or array of these components. These criteria provide a basis for understanding the generally mutually exclusive incidence of superconductivity and magnetism among the elements of the periodic table, although they can also be used to explain the occasional coexistence of superconductivity and ferromagnetism or antiferromagnetism in some materials. The molecular-orbital criteria for superconductivity complement existing formal theories in that they appear to explain simply and directly certain observed chemical trends of superconductivity, and are naturally applicable to superconducting materials lacking long-range crystalline order, such as solid-solution alloys, amorphous alloys, and small particles.
Document Details
- Document Type
- Technical Report
- Publication Date
- Dec 31, 1979
- Accession Number
- ADA079470
Entities
People
- D. D. Vvedensky
- Keith H. Johnson
- R. P. Messmer
Organizations
- Massachusetts Institute of Technology