Related papers: Low-temperature anharmonicity of barium titanate: …
We discuss the influence of a zero-temperature environment on a coherent quantum system. First, we calculate the reduced density operator of the system in the framework of the well-known, exactly solvable model of an oscillator coupled to a…
We report modifications of the ferroelectric and electrocaloric properties of BaTiO$_3$ by defects. For this purpose, we have combined \textit{ab initio}-based molecular dynamics simulations with a simple model for defects. We find that…
The perovskite BaBiO$_3$ crystallizes in a cubic structure and undergoes structural transitions toward lower symmetry phases upon cooling. The two low-temperature monoclinic phases are insulating, and the origin of this unexpected…
We present a method, based on a non-Markovian Langevin equation, to include quantum corrections to the classical dynamics of ions in a quasi-harmonic system. By properly fitting the correlation function of the noise, one can vary the…
Layered perovskite lithium yttrium titanate ($\rm LiYTiO_4$) has recently emerged as a promising low-potential, ultrahigh-rate intercalation-type anode material for lithium-ion batteries; however, its lattice dynamics and thermal transport…
We present the electrodynamic response of TiOBr, which undergoes a transition to a spin-singlet ground state for temperatures below T$_{C1}=28$ K. The temperature evolution of the phonon anomalies indicates, like in \cl, an extended…
The investigation of the structural phase transition in the vicinity of the Curie temperature $T_c$ of LiNb$_{1-x}$Ta$_x$O$_3$ crystals is motivated by the expected combination of advantageous high-temperature properties of LiNbO$_3$ and…
We investigate the temperature-pressure phase diagram of BaTiO_3 using a first-principles effective-Hamiltonian approach. We find that the zero-point motion of the ions affects the form of the phase diagram dramatically. Specifically, when…
The quantum dynamics of a two-level system coupled to an Ohmic spin- bath is studied by means of the perturbation approach based on a unitary transformation. A scattering function $\xi_k$ is introduced in the transformation to take into…
The molecular dynamics of solid benzene are extremely complex; especially below 77 K, its inner mechanics remain mostly unexplored. Benzene is also a prototypical molecular crystal that becomes energetically frustrated at low temperatures…
Effects of pressure and temperature on structural and thermodynamic properties of ice VII have been studied by using path-integral molecular dynamics (PIMD) simulations. Temperatures between 25 and 450 K, as well as pressures up to 12 GPa…
Modeling ferroelectric materials from first principles is one of the successes of density-functional theory, and the driver of much development effort, requiring an accurate description of the electronic processes and the thermodynamic…
We develop a method for investigating nonequilibrium dynamics of an ultracold system that is initially at thermal equilibrium. Our procedure is based on the classical fields approximation with appropriately prepared initial state. As an…
Understanding collective phenomena in quantum materials from first principles is a promising route toward engineering materials properties on demand and designing new functionalities. This work examines the quantum paraelectric state, an…
We study charge and energy transfer in two-site molecular electronic junctions in which electron transport is assisted by a vibrational mode. To understand the role of mode harmonicity/anharmonicity on transport behavior, we consider two…
We study transient thermal processes in infinite harmonic crystals with complex (polyatomic) lattice. Initially particles have zero displacements and random velocities such that distribution of temperature is spatially uniform. Initial…
The effects of quantum and thermal corrections on the dynamics of a damped nonlinearly kicked harmonic oscillator are studied. This is done via the Quantum Langevin Equation formalism working on a truncated moment expansion of the density…
Results of low temperature dielectric measurements on the mixed (Ca_(1-x)Pb_(x))TiO_(3) system are presented to show that a dielectric anomaly appears for x \geq 0.10. The observed dielectric peak is shown to be due to a thermodynamic phase…
The transition temperature between the low-temperature alpha phase of tin to beta tin is close to the room temperature (Tab =13C), and the difference in cohesive energy of the two phases at 0 K of about dEcoh=0.02 eV/atom is at the limit of…
Decoherence effects at finite temperature (T) are examined for two manifestly quantum systems: (i) Casimir forces between parallel plates that conduct along different directions, and (ii) a topological Aharonov-Bohm (AB) type force between…