First-principles computation of second-order elastic constants and equations of state for tetragonal BaTiO3

Second‐order elastic constants of hexagonal hydroxylapatite (P63) fromab initioquantum mechanics: Comparison between DFT functionals and basis sets

“…For further details on the ELASTCON approach, we suggest the reader to refer to the work of Perger and coworkers . The algorithm was used with good results in the calculation of the thermochemical‐physical properties of BaTiO 3 , rutile TiO 2 and talc . To ease the comparison between the two QM codes, we considered for each required unit cell deformation a three‐points displacement (NUMDERIV = 3 in CRYSTAL, NFREE = 2 in VASP) with a step of 0.015 Å (STEP and POTIM keywords in CRYSTAL and VASP, respectively).…”

“…Dispersive interactions were included in the quantum-mechanical treatment via the DFT-D2 and Tkatchenko-Scheffler schemes. The calculated bulk, shear, and Young's moduli were in the range of [42][43][44][45][46][47][48][49][50][51] GPa, and 107-134 GPa, respectively. The axial moduli, K a and K b , were instead in the range of 277-322 GPa and 506-509 GPa.…”