Structural phase transitions in calcium: A first principle calculation

In this paper we report the results of ab-initio pseudopotential calculations of the pressure induced phase transformations in calcium. Besides the interest whether first principle calculations can reproduce accurately the experimental results for the phase transition for the Ca, we also investigate the cause of this phase transition from fcc-bce and bcc-se by looking at their charge density and band structure. In this paper we have evaluated the lattice parameter, cohesive energy and bulk modulus and compared these with experimental results. It is found that there is a sharp change in the interatomic distances between the phases. Charge density maps give an intuitive picture of what is happening at the bcc-se phase transition and it is suggestive of Ca in the sc phase as having a structure of CsCl type ionic material of the type Ca-2+e(2)-.