Ab Initio Calculations of the Stability of a Vacancy in Na Clusters and Correlation with Melting

摘要: We report results of ab initio calculations on ${\mathrm{Na}}_{N},$ $N=55$, 147, and 309 clusters that show icosahedral growth to be most favorable in agreement with the recent photoelectron spectroscopy data. The structures are found significantly compressed central region. However, a vacancy at center or first shell is cost much higher energy compared other sites clusters. formation lowest vertex followed by edge cluster surface. These disordering easier happen surface region Recent experiments sodium also suggest premelting. Furthermore, we obtain value for $N=55$ case $N=147$ 309. This experimental finding melting temperature ${\mathrm{Na}}_{55}$. perturbation due mainly confined two atomic shells similar phenomena surfaces bulk metals.