Crossover between ionic/covalent and pure ionic bonding in magnesium oxyde clusters

TL;DR

This paper introduces an empirical model with fluctuating charges to study MgO clusters, capturing the transition from ionic to covalent bonding and predicting cluster structures and charge transfer behavior.

Contribution

It presents a novel empirical potential that accounts for polarization and models the crossover from ionic to covalent bonding in MgO clusters.

Findings

Predicts cuboid cluster structures consistent with previous studies.

Shows a smooth increase in charge transfer from 1 to 2 as cluster size grows.

Identifies a crossover size above 300 MgO molecules.

Abstract

An empirical potential with fluctuating charges is proposed for modelling (MgO)_n clusters in both the molecular (small n) and bulk (n->infty) regimes. Vectorial polarization forces are explicitely taken into account in the self-consistent determination of the charges. Our model predicts cuboid cluster structures, in agreement with previous experimental and theoretical results. The effective charge transferred between magnesium and oxygen smoothly increases from 1 to 2, with an estimated crossover size above 300 MgO molecules.