Related papers: Phase transitions in BaTiO$_3$ from first principl…
We revisit the phase diagram of BaTiO$_3$ under biaxial strain using a first principles-based effective Hamiltonian approach. We show that, in addition to the tetragonal ($c$), quasi-rhombohedral ($r$), and quasi-orthorhombic ($aa$)…
The ferroelectric property of BaTiO$_3$ crystal arises from the strong Pseudo Jahn-Teller (PJT) interactions between the non-degenerate ground electronic state, $^1A_{1g}$ and the degenerate $^1T_{1u}$ symmetry states through the nuclear…
Molecular Dynamics is applied to Ferroelectric Perovskites in the framework of a first-principles derived effective Hamiltonian (Zhong, Vanderbilt, Rabe, Phys. Rev. Lett. {\bf 73} (1994), 1861). The degrees of freedom, that obey the Newton…
We propose an order-disorder type microscopic model for BaTiO$_3$-like Ferroelectric Substance. Our model has three phase transitions and four phases. The symmetry and directions of the polarizations of the ordered phases agree with the…
We have begun a study of quantum ferroelectrics and paraelectrics. Simple 2D short-range lattice model hamiltonians are constructed, keeping in mind the phenomenology of real perovskite systems, like $SrTiO_{3}$ and $KTaO_{3}$. Pertinent…
The crystal structures and phonon spectra of orthorhombic cadmium titanate with the $Pbnm$ structure and of its two possible ferroelectrically distorted phases with $Pbn2_1$ and $Pb2_1m$ space groups were calculated from first principles…
A systematic study of the electronic structure in perovskite manganites is presented. The effective Hamiltonian is derived by taking into account the degeneracy of $e_g$ orbitals and strong electron correlation in Mn ions. The spin and…
We present an inexpensive first-principles approach for describing quantum paraelectricity that combines density functional theory (DFT) treatment of the electronic subsystem with quantum mechanical treatment of the ions through solution of…
The effect of inclusion of higher-order interactions in the {\it XY} model on critical properties is studied by Monte Carlo simulations. It is found that an increasing number of the higher-order terms in the Hamiltonian modifies the shape…
A first-principles study of the vibrational modes of PbTiO_3 in the ferroelectric tetragonal phase has been performed at all the main symmetry points of the Brillouin zone (BZ). The calculations use the local-density approximation and…
We show with first-principles molecular dynamics the persistence of intrinsic $\langle111\rangle$ Ti off-centerings for BaTiO$_3$ in its cubic paraelectric phase. Intriguingly, these are inconsistent with the Pm$\bar 3$m space group often…
The normal ferroelectric to paraelectric phase transition in model ferroelectric materials such as BaTiO3 is typically characterized by a sharp, well-defined dielectric constant peak at a specific transition temperature. However, under…
We used first-principles methods to perform a systematic search for potentially-stable phases of multiferroic BiFeO3. We considered a simulation cell compatible with the atomic distortions that are most common among perovskite oxides, and…
Monte Carlo simulations are used to examine cooperative creation of polar state in fluids of two-state particles with nonzero dipole in the excited state. With lowering temperature such systems undergo a second order transition from…
PbTiO$_3$ is a ferroelectric perovskite semiconductor with favourable electronic and optical properties, making it suitable for a wide range of applications, including photo-catalysis and (opto)electronic devices. Despite its relevance, an…
Using data obtained from first-principles calculations, we show that the position of the morphotropic phase boundary (MPB) and transition temperature at MPB in ferroelectric perovskite solutions can be predicted with quantitative accuracy…
We report a molecular dynamics study of ab initio quality of the ferroelectric phase transition in crystalline PbTiO3. We model anharmonicity accurately in terms of potential energy and polarization surfaces trained on density functional…
A second-principles effective interatomic potential is introduced for the prototypical perovskite CaTiO$_3$ (CTO), relying on a Taylor polynomial expansion of the Born-Oppenheimer energy surface around the cubic reference structure, in…
In order to understand the microscopic properties of the ferroelectric nanoparticles, we review concepts of the attractive BaTiO3 nanocrystals where a photon field from its constituent electrons and ions are considered. We present an…
A theoretical analysis of the internal structure of interphase boundaries separating domains of coexisting phases are presented for the perovskite ferroelectric BaTiO3. The temperature dependence of interphase boundary widths and surface…