Mechanical and dynamical stability of major oxide constituents of Portland cement clinker: a density functional theory study

Quantum-mechanical calculations based on the density functional theory (DFT) enable an effective characterization of a variety of properties of materials at the atomistic level, although at a high computational cost. Here, we fully exploit parallel computing to apply such methods to the study of lattice dynamics and mechanical response of the major oxide constituents of Portland cement clinker: (Formula presented.), (Formula presented.), (Formula presented.), and (Formula presented.). Raman spectra and the evolution of the elastic tensor (and associated mechanical properties) with pressure are predicted for all oxide systems. We devote much attention to the assessment of dynamical and mechanical stability of the many previously proposed polymorphic forms of the most abundant oxide: (Formula presented.). Specifically, five different crystalline models of (Formula presented.) are analyzed: only two turn out to be dynamically stable. The mechanical response of (Formula presented.) is further analyzed as a function of temperature through a quasi-harmonic description of its lattice dynamics.