Influence of water intercalation on the electronic structure of the hydrated Na0.3CoO2.yH2O using a local spin density approximation

TL;DR

This study investigates how water intercalation affects the electronic structure of hydrated Na0.3CoO2, revealing significant changes in charge density and orbital hybridization that influence its superconducting properties.

Contribution

It provides a detailed theoretical analysis of hydration effects on electronic structure using LSDA, aligning with experimental EELS data.

Findings

Decreased density in Co a1g state upon hydration

Rehybridization between O 2p and Co a1g orbitals

Hydration modifies interband excitations and dielectric functions

Abstract

The electronic band structures of the parent compound Na0.3CoO2 and the hydrated superconductor Na0.3CoO2.1.3H2O were evaluated using the local spin density approximation (LSDA). Systematic analysis on the bands near the Fermi surface (FS) revealed that the hydration-induced modifications appear, notably in the valence charge density and the orbital hybridization. The most striking changes are the decrease of density in Cobalt's a1g state and the rehybridization between O 2p and Co a1g in the hydrated superconducting phase. These hydration-induced modifications could yield visible differences in interband excitations and dielectric functions. Experimental results of electron energy-loss spectroscopy (EELS) are fundamentally in agreement with the theoretical predictions for the hydrated Na0.3CoO2.yH2O.