First-principles study of the rocksalt-cesium chloride relative phase stability in alkali halides -: art. no. 144112

We present a detailed investigation of observable properties associated with the relative stability of the rocksalt (B1) and cesium chloride (B2) phases in the AX (A=Li, Na, K, Rb, Cs; X=F, Cl, Br, I) crystal family. Thermodynamic B1-->B2 transition pressures and DeltaY=Y(B2)-Y(B1) differences in total energies, volumes, and bulk moduli at zero and transition pressures are computed following a localized Hartree-Fock method. The arrangement of the data in clear trends is shown to be mainly dominated by the cation atomic number. This behavior is well interpreted in terms of a variety of microscopic arguments that emerge from (i) the evaluation of the energy Hessian at the B1 and B2 points and (ii) the decomposition of the energy and pressure in anionic and cationic classical and quantum-mechanical contributions.