Dissociation channels ofNaN+clusters (3≤N≤37)

The dissociation of ${\mathrm{Na}}_{\mathit{N}}^{+}$ clusters (N≤37) has been studied using two cluster models and two different approximations to the exchange and correlation effects. First we show that the jellium model with the usual local-density approximation to exchange and correlation leads to dissociations mostly involving ${\mathrm{Na}}_2$ and ${\mathrm{Na}}_8$. This prediction does not agree with recent experimental results, which indicate that most ${\mathrm{Na}}_{\mathit{N}}^{+}$ clusters dissociate emitting a neutral monomer. The explicit introduction of the ions eliminates many dissociations involving ${\mathrm{Na}}_2$ in favor of the channel involving a Na monomer. Furthermore, a nonlocal description of exchange and correlation lowers the stability of ${\mathrm{Na}}_8$ in favor, again, of dissociation through the monomer channel. In summary, the combined effect of these two improvements leads to a satisfactory description of the dissociation of ${\mathrm{Na}}_{\mathit{N}}^{+}$ in comparison with experiment.