Morphology of the GdVO₄ crystal: first-principles studies

The present paper reports a theoretical investigation based on first-principles density functional theory calculations to predict the external morphology of the tetragonal GdVO₄ crystal from its internal structure. The Bravais-Friedel-Donnay-Harker (BFDH) method, attachment energy (AE) method and surface energy (SE) method were used in this study. Slice energies (cohesive, attachment and specific surface) of the three main crystal faces having (110), (101) and (200) orientation and their d_hkl thicknesses were computed using CRYSTAL17 code, in the frame of a 2D periodic slab model. The relative growth rate (R_hkl) and the morphological importance (MI_hkl) for each unrelaxed and relaxed (hkl) face of interest were determined. Consequently, the crystal shapes predicted based upon BFDH, AE and SE methods were represented by the Wulff construction. The results of the morphology crystal predictions, based on the above methods, were compared both against each other and against the experimentally observed morphologies. A quite satisfactory agreement between the predicted and observed crystal morphologies is noticed.