Ab initio statistical mechanics of the ferroelectric phase transition in<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msub><mml:mrow><mml:mi mathvariant="normal">PbTiO</mml:mi></mml:mrow><mml:mrow><mml:mn>3</mml:mn></mml:mrow></mml:msub></mml:mrow></mml:math>

Waghmare, Umesh V.; Rabe, Karin M.

doi:10.1103/physrevb.55.6161

Cited by 328 publications

(183 citation statements)

References 44 publications

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“…The tetragonal c/a ratio at 0 K (obtained by extrapolating lattice parameters) is 1.104 which is overestimated compared to the experimental value (1.071 at 0 K) 14 . It is clear that SCAN-based predictions of the transition temperatures of the three oxides improve over those of LDA-based parameters 8,46 .…”

Section: Simulationsmentioning

confidence: 97%

“…8) 8,46 . For KNbO 3 , local (κ 2 ) and short-range interaction parameters (j 1 , j 2 and j 4 ) are different from earlier theoretical results using WC-GGA 26 .…”

Section: Effective Hamiltonianmentioning

confidence: 99%

“…First-principles density functional calculations have been used extensively in microscopic studies of structural transitions via identifying the responsible phonon mode for structural transition, studying the stability of the intermediate phases and predicting transition temperatures (T C ) 4,7-9 . It has been established that harmonic and anharmonic couplings between phonons and strain-phonon coupling constants are the most crucial parameters that govern the phase transitions in perovskites 4,8,10 . Accuracy in determination of these parameters and subsequent estimation of transition temperatures is naturally limited by the DFT errors in estimation of lattice constants.…”

Section: Introductionmentioning

confidence: 99%

“…Also, the value of T C of PbTiO 3 using interaction parameters (calculated using LDA) at the experimental lattice constant is underestimated 8 . On the other hand, the gradient density approximation (GGA) mostly overestimates the lattice constants and gives supertetragonal structures of PbTiO 3 and BaTiO 3 14 .…”

Section: Introductionmentioning

confidence: 99%

“…Instead, an approximate approach is adopted that uses an effective Hamiltonian, which focuses on the low-energy structural configurations in MD or MC simulations 7,8 . Thus, there are two sources of errors in first-principles description of ferroelectric transitions: (a) ones arising from the choice of DFT functional, and (b) ones arising from the truncation of the set of configurations through the effective Hamiltonian.…”

Section: Introductionmentioning

confidence: 99%

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Accuracy of first-principles interatomic interactions and predictions of ferroelectric phase transitions in perovskite oxides: Energy functional and effective Hamiltonian

et al. 2017

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While first-principles density functional theory (DFT) based models have been effective in capturing the physics of ferroelectric phase transitions in BaTiO 3 , PbTiO 3 and KNbO 3 , quantitative estimates of the transition temperatures (T C 's) suffer from errors that are believed to originate from the errors in estimating lattice constants obtained within local density (LDA) and gradient density (GGA) approximations of DFT. The recently-developed strongly constrained and appropriately normed (SCAN) meta-GGA functional has been shown to be quite accurate in estimation of lattice constants. Here, we present a quantitative analysis of the estimates of ferroelectric ground state properties of eight perovskite oxides and transition temperatures of BaTiO 3 , PbTiO 3 and KNbO 3 obtained with molecular dynamics (MD) simulations using an effective Hamiltonian derived from the SCAN meta-GGA based DFT. Relative to LDA, we find an improvement in estimates of T C 's, which arises from the changes in calculated strain-phonon, anharmonic coupling constants and strength of ferroelectric instabilities, i.e., frequencies of the soft modes. We also assess the errors in T C originating from approximately integrating out the high-energy phonons during construction of the model Hamiltonian through estimates of the effects of fourth-order couplings between soft mode and higher energy modes of BaTiO 3 , PbTiO 3 and KNbO 3 . We find that inclusion of these anharmonic couplings results in deeper double-well energy functions of ferroelectric distortions and further improvement in the estimates of transition temperatures. Consistently improved estimates of lattice constants and transition temperatures with the SCAN meta-GGA calculations augur well for their use in simulations of superlattices or hetero-structures of perovskite oxides, in which the effects of lattice matching are critical.

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Section: Simulationsmentioning

confidence: 97%

“…8) 8,46 . For KNbO 3 , local (κ 2 ) and short-range interaction parameters (j 1 , j 2 and j 4 ) are different from earlier theoretical results using WC-GGA 26 .…”

Section: Effective Hamiltonianmentioning

confidence: 99%