Pair correlation and dynamic Jahn-Teller effect: high Tc in nanoclusters

Electronic states in metallic nanoclusters form energy shells and degree of their filling depends on the number of delocalized electrons. In the region close to half-filling the cluster geometry oscillates between the prolate and oblate configurations (dynamic Jahn-Teller effect). For large clusters this effect competes with pair correlation and, as a result, it is perfectly realistic to observe the transition to the superconducting state. For some clusters the value of the critical temperature is rather high, near 140K