Real-space charge distribution of the cobalt ion and its relation with charge and spin states

TL;DR

This paper investigates the real-space charge distribution of cobalt ions in different charge and spin states, revealing minimal static charge transfer but small variations in integrated charges across states.

Contribution

It provides a detailed analysis of the physical meaning of charge states in cobalt compounds, challenging the traditional electron transfer explanation.

Findings

No prominent static charge transfer observed.

Small variations in integrated charges correlate with different states.

Charge distribution is more complex than simple electron transfer models.

Abstract

The charge state of an ion provides a simplified electronic picture of the bonding in compounds, and heuristically explains the basic electronic structure of a system. Despite its usefulness, the physical and chemical definition of a charge state is not a trivial one, and the essential idea of electron transfer is found to be not a realistic explanation. Here, we study the real-space charge distribution of a cobalt ion in its various charge and spin states, and examine the relation between the formal charge/spin states and the static charge distribution. Taking the prototypical cobalt oxides, La/SrCoO$_3$, and bulk Co metal, we confirm that no prominent static charge transfer exists for different charge states. However, we show that small variations exist in the integrated charges for different charge states, and these are compared to the various spin state cases.