Electric response properties of neutral and charged Al13X (X = Li, Na, K) magic clusters. A comprehensive ab initio and density functional comparative study

A systematic analysis of the dipole polarizabilities and first hyperpolarizabilities of a cluster series based on the magic Al13 cluster is presented. Reliable values of the dipole polarizabilities and first hyperpolarizabilities of Al13X0/−1 (X = Li, Na, K) by means of ab initio and density functional theory clusters are for the first time provided and discussed. In addition, useful information involving the partitioning of the dipole polarizabilities in terms of intrinsic polarizabilities computed with the fractional occupation iterative Hirshfeld method (FOHI) are illustrated. Finally, a step by step study of the polarization mechanism dominating the hyperpolarizabilities of these species is illustrated and explained in a comprehensive manner. The presented outcomes point out a monotonic (hyper)polarizability evolution going from Li to K for both neutral and charged cluster families. Also, it is clearly shown that all neutral clusters become largely more (hyper)polarizable and more anisotropic after receiving one electron. Concerning the principal hyperpolarization mechanism in these species, the presented analysis suggests that is mainly unidirectional in character, involving intense charge transfer processes from the metal cluster to the alkali metal.