We review recent advances made by our group in finding optimized geometries of atomic clusters as well as in description of fission of charged small metal clusters. We base our approach to these problems on analysis of multidimensional potential energy surface. For the fusion process we have developed an effective scheme of adding new atoms to stable cluster isomers which provides good starting points for a global optimization procedure and thus allows one to obtain optimal geometries of larger clusters in an efficient way. We apply this algorithm to finding geometries of metal and noble gas clusters. For the fission process the analysis of the potential energy landscape calculated on the ab initio level of theory allowed us to obtain very detailed information on energetics and pathways of the different fission channels for the Na2+10 clusters.
General information about the problem of determining ground-state geometries of atomic clusters has been given. Modified diffusion Monte Carlo (MDMC) method which was recently developed for this problem has been reviewed. A technique, called the rotation operation, has been proposed to escape from local minima. Information about empirical potential energy functions, used in the computations, has been given. Binding energy results for Zn nCd m and (AlTiNi) n clusters obtained by the combination of the MDMC method and the rotation operation have been presented and these results have been compared with the molecular dynamics (MD) results. Efficiency of the method has been investigated by comparing the results and the computation times with the results of the single walker MDMC method - rotation operation combination.
Penrose (1974), in which atoms arrange them- selves into clusters with overlapping edges. Most recently, the perfect quasi-periodic tilings have been interpreted in terms of simple energetics that favors the formation of a single atomiccluster (Steinhard and Jeong 1996). Eglash (1999) and Gerdes (1999