Quantitative analysis of the first-principles effective-Hamiltonian approach to ferroelectric perovskites

Abstract

The various approximations used in the construction of a first-principles effective Hamiltonian for BaTiO3, and their effects on the calculated transition temperatures, are discussed. An effective Hamiltonian for BaTiO3 is constructed not from first-principles calculations, but from the structural energetics of an atomistic shell model for BaTiO3 of Tinte et al. This allows the elimination of certain uncontrolled approximations that arise in the comparison of first-principles effective Hamiltonian results with experimental values and the quantification of errors associated with the selection of the effective Hamiltonian subspace and subsequent projection. The discrepancies in transition temperatures computed in classical simulations for this effective Hamiltonian and for the atomistic shell model are shown to be associated primarily with a poor description of the thermal expansion in the former case. This leads to specific proposals for refinements to the first-principles effective Hamiltonian method. Our results suggest that there are at least two significant sources of error in the effective-Hamiltonian treatment of BaTiO3 in the literature, i.e., the improper treatment of thermal expansion, and the errors inherent in the first-principles approach itself.

9 pages with 2 postscript figures embedded. Uses REVTeX4. Also available at http://www.physics.rutgers.edu/~dhv/preprints/st_heff/

References in corpus (7)

• First-principles theory of ferroelectric phase transitions for perovskites: The case of BaTiO3
• Phase transitions in BaTiO${}_3$ from first principles
• Finite-temperature properties of PZT alloys from first principles
• Ab initio statistical mechanics of the ferroelectric phase transition in PbTiO3
• First-principles study of the temperature-pressure phase diagram of BaTiO3
• Applications of the generalized gradient approximation to ferroelectric perovskites
• Optimized local modes for lattice dynamical applications

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• Thermodynamics and dielectric response of ${\text{BaTiO}}_3$ by data-driven modeling
• The electrocaloric effect in BaTiO${}_3$ at all three ferroelectric transitions: anisotropy and inverse caloric effects
• Switching a polar metal via strain gradients
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• Thermal disorder and phonon softening in the ferroelectric phase transition of lead titanate
• A new look at the temperature-dependent properties of the antiferroelectric model PbZrO3: an effective Hamiltonian study