First-principles energetics and structural relaxation of antigorite

We have investigated the antigorite m = 17 structure [Mg48Si34O85(OH)62] by density functional theory (DFT), with the aim to probe the method on such a large and low symmetry (Pm) system. We found a satisfactory match with the experiments using both LDA and GGA approximations to exchangecorrelation, although the former performs slightly better here. Predicted cell constants are within 0.3% for LDA, and 0.5% for GGA, of the experimental values....