Temperature dependence of the polarizability of sodium clusters:: An all-electron density functional study

In this contribution we report first-principle all-electron density functional theory (DFT) calculations on small sodium clusters with less than 10 atoms employing the linear combination of Gaussian type orbital DFT program deMon2k. Born-Oppenheimer molecular dynamics (BOMD) simulations over more than 200 ps (> 100,000 time steps) with gradient corrected functionals in combination with DFT optimized all-electron double-zeta valence polarization are presented. In order to study the temperature dependency of the cluster polarizabilities BOMD trajectories from 50 to 900 K are recorded for each cluster. The polarizability tensor is then calculated along these trajectories employing all-electron triple-zeta valence polarization basis sets augmented with field induced polarization functions. The analysis of the BOMD results shows that the temperature dependency of the sodium cluster polarizability varies strongly with cluster size. Moreover, characteristic changes in the polarizability per atom as a function of temperature are observed. The mismatch between theoretical and experimental polarizabilities will be discussed in the light of these new results.