\textit{Ab initio} study of the possibility of noncollinear magnetism in small Mn clusters

We investigated the possibility of noncollinear magnetism in small Mn$_{n}$ clusters ($n$ = 2-6) using the density-functional method SIESTA with the generalized gradient approximation (GGA) to exchange and correlation. The lowest-energy states identified were ferromagnetic for Mn$_{2}$ and Mn$_{3}$, and magnetically noncollinear for Mn$_{4}$, Mn$_{5 }$ and, most decidedly, Mn$_{6}$. These SIESTA/GGA results, which are compared with those of an earlier SIESTA study that used the local spin density approximation, are qualitatively in keeping with the result obtained by VASP/GGA calculations.