Volume change of bulk metals and metal clusters due to spin-polarization

Abstract

The stabilized jellium model (SJM) provides us a method to calculate the volume changes of different simple metals as a function of the spin polarization, $\zeta$, of the delocalized valence electrons. Our calculations show that for bulk metals, the equilibrium Wigner-Seitz (WS) radius, ${\bar{r}}_s(\zeta )$, is always a n increasing function of the polarization i.e., the volume of a bulk metal always increases as $\zeta$ increases, and the rate of increasing is higher for higher electron density metals. Using the SJM along with the local spin density approximation, we have also calculated the equilibrium WS radius, ${\bar{r}}_s(N,\zeta )$, of spherical jellium clusters, at which the pressure on the cluster with given numbers of total electrons, $N$, and their spin configuration $\zeta$ vanishes. Our calculations f or Cs, Na, and Al clusters show that ${\bar{r}}_s(N,\zeta )$ as a function of $\zeta$ behaves differently depending on whether $N$ corresponds to a closed-shell or an open-shell cluster. For a closed-shell cluster, it is an increasing function of $\zeta$ over the whole range $0\le \zeta \le 1$, whereas in open-shell clusters it has a decreasing behavior over the range $0\le \zeta \le {\zeta }_0$, where ${\zeta }_0$ is a polarization that the cluster has a configuration consistent with Hund's first rule. The resu lts show that for all neutral clusters with ground state spin configuration, ${\zeta }_0$, the inequality ${\bar{r}}_s(N,{\zeta }_0)\le {\bar{r}}_s(0)$ always holds (self-compression) but, at some polarization ${\zeta }_1>{\zeta }_0$, the inequality changes the direction (self-expansion). However, the inequality ${\bar{r}}_s(N,\zeta )\le {\bar{r}}_s(\zeta )$ always holds and the equality is achieved in the limit $N\to \infty$.

7 pages, RevTex, 10 figures

References in corpus (1)

• Finite-size effects and the stabilized spin-polarized jellium model for metal clusters

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