Density Functional Study of Li_nH_m Clusters. Electric Dipole Polarizabilities

Abstract

The dipole polarizability of a series of clusters of the type Li n H m has been calculated using density functional methods. The study of the trends in the mean polarizability and the anisotropy are explained in terms of the interplay between electronic and geometrical effects. The changes in the polarizability for different isomers of a given cluster as well as its variations when hydrogen atoms are added to a given cluster are also discussed. A very related quantity, the hardness, has also been calculated in the simple approximation of hardness equal to the energy gap. Their values are discussed in terms of the possible stability of the different clusters.

Enhanced Linear and Nonlinear Polarizabilities for the Li4 Cluster. How Satisfactory Is the Agreement between Theory and Experiment for the Static Dipole Polarizability?

“…The structure and properties of lithium clusters have emerged as an intensively active research field in recent years. Experimental − and theoretical − studies have explored various chemical and physical aspects of these systems. A very recent experimental study 3 of the static dipole polarizability of lithium clusters paved the way to systematic explorations of the electric properties of such systems.…”

On the Density Functional Relationship between Static Dipole Polarizability and Global Softness

“…Since an exact expression for the local softness is not known, the evaluation of eq 5 can be done only by resorting to some model for the softness. Hence, in this work the local softness proposed in ref will be used where c is an adjustable parameter and ρ( r ) the spherical averaged electron density. For atoms, the electron density in the valence region can be approximated by …”

Links among the Fukui potential, the alchemical hardness and the local hardness of an atom in a molecule

“…If approximations for the exchange‐correlation functional are available, approximations for the hardness kernel and frontier local hardness are straightforwardly deduced from the definition of F[ρ] 37 and Equation () and In these equations is the kinetic energy of the Kohn‐Sham noninteracting system, and is the exchange‐correlation energy functional 38 . Note that the first term in the last equation is nothing but the Fukui potential 39 .…”