Structure and electronic properties of Al14 and Al13Na clusters

Ab initio molecular dynamics simulations on Al-14 cluster show that in the capped icosahedron structure of this cluster, the 3s electrons of the capping Al atom behave more like core electrons giving rise to an electronic shell closure effect known for simple metal clusters with 40 valence electrons and which we also find for Al13Na. This makes the two clusters magic. Al-14 has a higher binding energy as compared to Al-13. However, the highest occupied and the lowest unoccupied molecular orbital gap in Al-14 is lower than in Al-13 whereas in the case of Al13Na it increases. These results are in complete agreement with the observation of a lower ionization potential for Al-14 and a higher ionization potential for Al13Na. [S0163-1829(98)03711-4].