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University of Pennsylvania

Density Functional Theory

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Full-Text Articles in Engineering Science and Materials

First Principles Studies Of Magnetic Oxides, Spin-Driven Ferroelectricity, And The Effect Of Polarization In The Chemistry Of Functional Heterointerfaces, Diomedes Saldana-Greco Jan 2016

First Principles Studies Of Magnetic Oxides, Spin-Driven Ferroelectricity, And The Effect Of Polarization In The Chemistry Of Functional Heterointerfaces, Diomedes Saldana-Greco

Publicly Accessible Penn Dissertations

Achieving accurate description and understanding of the chemical and physical properties of complex materials enables the further development of their technological applications. Employing density functional theory (DFT) with rotationally invariant Hubbard corrections, we present an extensive study of binary manganese oxides modeling their noncollinear spin patterns and computing their electronic structures in agreement with experimental results. Leveraging on our success in predicting accurately magnetic properties, we explore the noncollinear cycloidal magnetic order in CaMn$_{7}$O$_{12}$, which breaks inversion symmetry generating one of the largest spin-driven ferroelectric polarizations measured to date. Based on a generalized spin-current model ...


Multiscale Simulations Of Dynamics Of Ferroelectric Domains, Shi Liu Jan 2015

Multiscale Simulations Of Dynamics Of Ferroelectric Domains, Shi Liu

Publicly Accessible Penn Dissertations

Ferroelectric materials exhibiting switchable polarization have been used as critical components in electronics, memory, actuators and acoustics, and electro-optics. The applications of ferroelectric materials heavily rely on the interactions between the polarization and external perturbations, such as electric field, stress, and temperature. It is therefore crucial to understand the dynamics of ferroelectric response at finite temperature. Despite the tremendous advance of computational power and the success of first-principles methods, large-scale simulations of dynamics in oxides at finite temperature can still only be performed using classical atomistic potential. We first develop a model potential based on principles of bond-valence and bond-valence ...