Effects of spin orbital coupling on atomic and electronic structures in Al2Cu and Al2Au crystal and liquid phases via ab initio molecular dynamics simulations

• The SOC effect affects the cohesion energy of crystal phase.
• The effect of SOC was reduced due to random local atomic structures in liquids.
• The local geometrical structures also affect the melting points.
• Both SOC effect and local atomic structures are important for melting point difference.

The origin of different melting points between Al2Cu and Al2Au has been studied using ab initio molecular dynamics simulations. Cohesive energy, electronic structures and structure information of both crystal and liquid phases have been analyzed. It is found that spin orbital coupling (SOC) plays an important role on the cohesive energy of crystal phase, consistent with the different melting points of these two alloys. Whereas, it seems that SOC has no effect on the formation energy and structure of liquid phase. Possible mechanism of reduced SOC effect at liquid phase is proposed. Our results are helpful to understand the glass formation ability difference between Al2Cu and Al2Au.