Fig. 9: Results of the MD simulations with an externally applied negative pressure p = −2 GPa.
From: Thermodynamics and dielectric response of BaTiO3 by data-driven modeling
Panel a shows the chemical potential differences across the T-C transition, obtained via NST fully flexible simulations and with an estimated Curie temperature of Tc = (264 ± 1) K, as opposed to (182.4 ± 0.7) K calculated at ambient pressure (see subsection “Thermodynamics of BaTiO3”). Panel b shows instead a comparison between the time evolution of the lattice constant in NpT simulations at 250 K with negative pressure and ambient pressure. These show how the effect of a negative pressure slightly increases the average unit-cell lattice parameter (by only 0.7%) due to the large bulk modulus of BaTiO3. This has, however, important consequences on the relative stability of T and C phases, with a shift of the Curie point of 82 K with respect to the ambient pressure estimate. Error bars have the same meaning as in Fig. 6.
