Resonating valence-bond mechanism for the superconductivity in K _3C_(60)

摘要

Density functional theory calculations in different cluster models, the largest one K_(38)(C_(60))_(23) with 1,418 atoms, combined with the resonating valence-bond theory show that superconductivity in K_3C_(60) involves interaction of C_(60) with K ~+, K~0, and K~- in octahedral interstices as well as immobilization of negative charges on positive tetrahedral K atoms. We found that the orbitals involved in the highest occupied molecular orbital-lowest unoccupied molecular orbital gap are mainly from C_(60) and octahedral potassium atoms. We suggest that a K_3C_(60) superconductor improvement can be achieved through potassium atom vacancy in octahedral sites.