First principles account for large changes in electronic structure and bonding from LaCu to LaCuMg and LaCuMg4

Abstract

Increasing amounts of magnesium in LaCu intermetallic are shown to bring drastic electronic, chemical and mechanical changes. Based on DFT methodologies this is quantified for the cohesive energies, relative charge transfers, bulk modules, electronic structures and bonding properties for the three compounds LaCu, LaCuMg and LaCuMg4. Particularly the cohesive energies increase with Mg amounts. This is illustrated by the increasing number of pair interactions: While in the binary the bonding is ensured by La–Cu, in the ternaries La–Cu, La–Mg and Cu–Mg interactions contribute to the bonding with the extra electrons brought by Mg occupying bonding states. Along the series, increasing magnesium contents lead to moderate increase of the compressibility.