Mutual information in conjugate spaces for neutral atoms and ions

Abstract

The discrepancy among one-electron and two-electron densities for diverseN-electronatomss, enclosing neutral systems (with nuclear chargeZ=N) and charge-one ions (|N−Z|=1), isquantified by means of mutual information,I, and Quantum Similarity Index,QSI, in the conjugatespaces position/momentum. These differences can be interpreted as a measure of the electroncorrelation of the system. The analysis is carried out by considering systems with a nuclear chargeup toZ=103and singly charged ions (cations and anions) as far asN=54. The interelectroniccorrelation, for any given system, is quantified through the comparison of its double-variable electronpair density and the product of the respective one-particle densities. An in-depth study along thePeriodic Table reveals the importance, far beyond the weight of the systems considered, of theirshell structure.