相关论文: Phase Stability of TiO$_2$ Polymorphs from Diffusi…
The ferroelectric trends of rutile (TiO$_2$) in bulk and at the (110) surface are investigated by means of ab initio density functional theory. We discuss the underlying mechanism of the incipient ferroelectric behavior of rutile in terms…
Using kinetic Monte Carlo simulations and a bond-counting ansatz, thermal stability and diffusion of an adatom island on a crystal surface are studied. At low temperatures, the diffusion constant $D$ is found to decrease for a wide range of…
We report a single crystal neutron and x-ray diffraction study of the hybrid improper multiferroic Ca3Mn1.9Ti0.1O7 (CMTO), a prototypical system where the electric polarization arises from the condensation of two lattice distortion…
It has been recently established by NMR techniques that in the high temperature cubic phase of BaTiO$_3$ the Ti ions are not confined to the high symmetry cubic sites, but rather occupy one of the eight off-center positions along the…
A first-principles atomic orbital-based electronic structure method is used to investigate the low index surfaces of rutile Titanium Dioxide. The method is relatively cheap in computational terms, making it attractive for the study of oxide…
We describe a first-principles statistical mechanics approach enabling us to simulate the steady-state situation of heterogeneous catalysis. In a first step density-functional theory together with transition-state theory is employed to…
We have used a tight-binding model that is fit to first-principles electronic-structure calculations for titanium to calculate quasi-harmonic phonons and the Gibbs free energy of the hexagonal close-packed (hcp) and omega crystal…
An atomistic effective Hamiltonian technique is used to investigate the finite-temperature energy storage properties of a ferroelectric nanocomposite consisting of an array of BaTiO$_{3}$ nanowires embedded in a SrTiO$_{3}$ matrix, for…
The prediction of new high entropy oxides (HEOs) remains a profound challenge due to their inherent chemical complexity. In this work, we combine experimental and computational methods to search for new HEOs in the tetravalent $A$O$_2$…
Tantalum pentoxide (Ta2O5) is a wide-gap semiconductor which has important technological applications. Despite the enormous efforts from both experimental and theoretical studies, the ground state crystal structure of Ta2O5 is not yet…
The influence of the electric field and electric current on the behavior of oxygen vacancies (VOs) in TiO2 anatase was investigated with Scanning Tunneling Microscopy (STM). At the anatase (101) surface VOs are not stable; they migrate into…
It is well known that conventional harmonic lattice dynamics cannot be applied to energetically unstable crystals at 0 K, such as high temperature body centered cubic (BCC) phase of crystalline Zr. Predicting phonon spectra at finite…
Monte Carlo simulations, supplemented by ab initio calculations, shed light into the energetics and thermodynamic stability of nanostructured amorphous carbon. The interaction of the embedded nanocrystals with the host amorphous matrix is…
Defects in semiconductors can exhibit multiple charge states, which can be used for charge storage applications. Here we consider such charge storage in a series of oxygen deficient phases of TiO$_2$, known as Magn\'eli phases. These…
New interatomic potentials describing defects, plasticity and high temperature phase transitions for Ti are presented. Fitting the martensitic hcp-bcc phase transformation temperature requires an efficient and accurate method to determine…
The structure of CO adsorbates on the Rh(110) surface is studied at full coverage using first-principles techniques. The relative energies of different adsorbate geometries are determined by means of accurate structure optimizations. In…
Vanadium dioxide undergoes a metal-insulator transition (MIT) from an insulating (monoclinic) to a metallic (tetragonal) phase close to room temperature, which makes it a promising functional material for many applications, e.g. as chemical…
We introduce an efficient scheme for the molecular dynamics of electronic systems by means of quantum Monte Carlo. The evaluation of the (Born-Oppenheimer) forces acting on the ionic positions is achieved by two main ingredients: i) the…
We have used an effective model of ferroelectric PbTiO$_{3}$, which displays a representative soft mode-driven phase transition, to investigate how different features of the potential-energy surface affect the transition temperature $T_{\rm…
The dynamic structures of the cubic and tetragonal phase in BaTiO3 and its dielectric response above the cubic-to-tetragonal phase transition temperature (Tp) are studied by first-principles molecular dynamics (MD) simulation. It's shown…