A unique situation for an endohedral metallofullerene

This letter demonstrates for the first time that an endohedral environment, such as the bucky-ball C-60, can produce a significant redistribution of o scillator strengths in endohedrally trapped atoms, making the dominant tran sitions no longer superior but inferior, and also making electron correlati ons in such atoms act in an opposite way to free atoms. This is exemplified by calculations of the oscillator strengths and photoionization cross sect ions of the Ca atom trapped inside C-60 Also, while photoionization cross s ections can undergo dramatic changes on confinement, the photoelectron angu lar asymmetry parameter beta(nl) can, in contrast to natural expectation, r emain largely unchanged. The random-phase approximation with exchange was e mployed. We believe these are the first calculations of electron correlatio ns for confined atomic species.