LAUSR

Abstract The first-principles calculations based on the density functional theory (DFT) were employed to investigate the effect of rare earth (RE) elements (La, Ce, Pr and Nd) doping on diopside CaMgSi2O6. The formation energy of the investigated structures reveals that theses RE atoms preferentially replaces Ca atom in diopside. RE dopants contribute more valence electrons to the bonding, and the directionality and locality of the charge accumulation around the RE atoms are continuously enhanced with the increasing of a number of RE-f electrons. The mechanical properties of the compounds were discussed based on the calculations of the elastic constants, and the results indicate that La doping decreases the bulk modulus, shear modulus and Young's modulus of diopside, while the rest three RE elements exhibit the reverse effect. The anisotropy factor results indicate that RE doping reduce the degree of anisotropy of diopside and consequently suppresses the generation of micro-cracks.