Gupta potential for alkaline earth metals: Calcium and strontium

Empirical Gupta-type potentials have been developed for alkaline earth metals, Ca and Sr. The potential parameters were fitted according to the experimental lattice constants, cohesive energies and elastic constants. Compared to experiments and DFT calculations, our potentials can reproduce the bulk modulus, shear modulus, and sound speed very well. More importantly, our potentials can also describe phonon dispersion relationships of Ca and Sr solids correctly. Energy profiles for fcc–bcc transformation along the Bain deformation path has been calculated, which yields the correct energy difference between fcc and bcc phases. Our potentials are also applied to the low-coordination environments, i.e., vacancy formation energies and surface energies of low-index surfaces, and a qualitative agreement with experiment and previous theoretical results is obtained.