Finite temperature behavior of impurity doped Lithium cluster, Li₆Sn

Abstract

We have carried out extensive isokinetic ab initio molecular-dynamic simulations to investigate the finite temperature properties of the impurity doped cluster Li₆Sn and the host cluster Li₇. The data obtained from about 20 temperatures and total simulation time of at least 3 ns is used to extract thermodynamical quantities like canonical specific heat. We observe that, first, Li₆Sn becomes liquidlike around 250 K, at much lower temperature than that for Li₇ ( ≈ 425 K). Second, a weak shoulder around 50 K in the specific heat curve of Li₆Sn is observed due to the weakening of Li-Li bonds. The peak in the specific heat of Li₇ is very broad and the specific heat curve does not show any premelting features.