Material optimization and modeling

The engineering of nanocomposites will be developed basing on modeling of the structural and functional properties. The first step is to optimize the parameters of the materials and to study their electronic structure, and piezo- ferro- and electro-caloric properties, using ab-initio and Monte Carlo simulations. The challenge here is how to improve the properties of one of the selected features without changing the other. The available ab- initio packages VIENNA and CRYSTAL will be explored at this stage. Then, home-made Monte-Carlo simulation routine will be adjusted to reveal the temperature–depended on the evolution of studied functionalities. At the next step, we shall take into account formation of self-organized topological excitations in the ferroelectric nanorods and nanodots. We shall calculate their piezo- ferroelectric properties, dynamical ultra-high-frequency response and multicaloric properties of such systems provided by functional textures cross-coupling. Simulations will rely on the standard Landau –Ginzburg - Devonshire (LGD) functional with gradient terms appropriate for the particular oxide materials and accounting for the depolarization and elastic forces by coupling with the corresponding energies. In addition to analytical techniques, we shall rely on the scalable high-performance codes that include electrostatic and electrostrictive couplings, and can easily incorporate realistic LGD functionals for various materials. Our starting point is establishing the conditions mostly for the formation of a particular kind of topological excitations in nanodots and nanorods. We plan to concentrate along two major lines motivated by experiment: (i) generating and manipulating topological defects in the nanorods and nanodots arrays by the applied electric field. Their switching properties with the creation of multivalued hysteresis loops (ii) The impact of the investigated effects on the ferro-piezoelectric properties of the nanocomposite materials. Calculations will be done mostly analytically using the time-dependent Landau-Pitaevsky approach, coupled with electrostatic, magnetostatic and elastic equations. The innovative challenge will be the integration of such formalism with thermodynamic heat-transfer equations, available in traditional engineering packages. This will permit to understand and explore the multicalloric effects in smart material nanostructures, having the nonlinear thermodynamic equation of states on the qualitatively new level.  Beyond the purely innovative aspects of theoretical analysis, consisting in the application of fundamental approach of theoretical physics to concrete engineering tasks (that is rarely done), we shall provide reliable and precise indications towards device optimization.