Comprehensively considering the adsorption energy and weighting of all possible adsorption 11 sites, the overall adsorption capacity of modifiers (Li, Be, Ca, Sr and Pb) on Mg2Si {100} and 12 {111} surfaces is evaluated by first-principles calculations. Furthermore, the ratio (δ) of weighted 13 total adsorption energy are developed to describe the competitive adsorption along <100> and 14 <111> directions, which could serve as a screen criterion for potential modifiers when regulating 15 Mg2Si into designed shapes. Our findings contribute to further understanding the morphological 16 evolution of Mg2Si during the growth process, and can be extended to other modified compounds.
