First-principles theoretical analysis of bulk and nano-scale functional materials

Abstract

Much needed advances in technology to tackle the problems of sustainable energy and environment requires continuous efforts to develop new functional materials and devices that are more energy efficient and eco-friendly. With continued advances in computational power, algorithms and techniques of simulations, computational material research plays a key role in predicting and engineering novel materials with desired properties. In particular, first-principles Density Functional Theory-based simulations provide fundamental insights into structural stability and properties of a material under the influence of external stimulii. On the other hand, classical atomistic modeling of materials helps in the study of their properties at long time and length scales through use of Molecular Dynamics or Monte Carlo simulations, possibly with effective Hamiltonian or model constructed from first-principles. This thesis is divided into three parts based on the kind of technological applications and functionality of the materials studied. The first part focuses on the microscopic understanding of the origin of inhomogeneously ordered domain structures in ferroelectric materials like PbTiO3 and BaTiO3 that can be tuned with electrical and mechanical boundary conditions. This has relevance to applications in nano-electro-mechanical systems (NEMS).