Density Functional Theory approaches for the investigation of the structural, vibrational and electronic properties of bulk dolomite, CaMg(CO3)2

Dolomite CaMg(CO3)2 (space group R3¯) is a carbonate mineral that is interesting for several and manyfold geological, mineralogical and technological applications. The present study reports a thorough investigation of the crystallographic, vibrational and electronic properties of dolomite using ab initio simulations at the Density Functional Theory (DFT) level. The effect of several DFT Hamiltonians i.e., LDA, GGA, hybrid functionals and meta-GGA coupled with dispersive forces correction methods (D3), with an all–electron Gaussian type orbitals (GTO) basis set, was also investigated, to understand which one performs better in describing the mineral properties. The equilibrium geometry, vibrational spectra (Raman and FT–IR), including the longitudinal optical–transverse optical (LO–TO) splitting, and electronic properties e.g., band structure and density of states (DOS) were calculated. The optimized geometry from DFT simulations was comparable to previous experimental single–crystal data, with cell volume differences from XRD refinements being small, between 1% and 4%. The calculated IR and Raman spectra are in good agreement with the experimental ones in terms of both the position and intensity of the vibrational bands, with better results obtained from hybrid functionals. The calculated band structures and density of states are in line with other theoretical results, confirming the insulating nature of this mineral.