4f wavefunction collapse and giant resonances in molecules

✍ Scribed by M.B. Robin

• Publisher: Elsevier Science
• Year: 1985
• Tongue: English
• Weight: 477 KB
• Volume: 119
• Category: Article
• ISSN: 0009-2614
• DOI: 10.1016/0009-2614(85)85415-4

✦ Synopsis

The effective polenlial for an f orbilal in an atom reflects both the attractive Coulomb and rcpulsrve centrifugal forces. resulting in a double-well polenual. Trans~lions from nd orbiials to i orbitals bound m Ihe inner well of rhe effective potential are unique in their frequency. mlensiry and response 10 external perturbauons, and are known as "gianr resonances". In molecules, the role or the repulsive cenu-ifugal force is played inslead by orthogonaliry lo bonding valence orbimls. in which case the inner-well wavefuncimns lhen become anlibonding valence MOs In general. the expected molecular giant resonances resuhmg from transitions between d-hke MOs and antlbonding valence MOs of Z symmetry are non seen because of strong valence/Rydberg mixing However, in cerlam molecules having high symmetries and ihe proper eleclronic configurations. this upper-slale mixing is symmetry forbidden. and so molecular giant resonances can appear. These d -P molecular gianl resonances are identified for Ihc first nmc in the vacuum-ulrrawolc~ specra or qclopropane cyclohcxanc neopenmne and uranium hcnafluonde.