Investigation of InP and SiGe nanomaterials via molecular dynamics simulations

Nayir, Nadire
In this dissertation, InP and Si/Ge nanomaterials were investigated via classical molec- ular dynamics simulations. Structural and dynamical properties of InP nanorods and nanoparticles were examined under different conditions such as heating, cool- ing, strain etc. In the second part of this dissertation, a ReaxFF reactive force field development has been targeted to provide a more generalized description for the sim- ulation of the crystallization process of amorphous Ge on Si substrate. For this aim, the ReaxFF reactive force developed by Fogarty et al. was re-parametrized for O- interstitial point defect formation in Si/SiO 2 interface. Additionally, the ReaxFF re- active force field initially parametrized by Zheng et al. was re-optimized for O-related point defect and its migration in Ge, and the heat treatment of Ge/GeO 2 interface. To establish the force field reliability, both force fields were subjected to the validation process further based on MD simulations.


A Modulus gradient elasticity model for nano-reinforced composites
Gülaşık, Hasan; Gürses, Ercan; Department of Aerospace Engineering (2018)
In this work, nanocomposites and their numerical simulations are studied. At the beginning of the study, the properties of the polymer nanocomposites are explained based on a specific nano-inclusion and polymer matrix couple, namely, carbon nanotube (CNT) and thermoplastic polyetheretherketone (PEEK) polymer. In a literature comparison study, it is shown that the properties of the constituents, interface properties, manufacturing methods, characterization methods and therefore mechanical properties of the C...
Demonstration of optical nonlinearity in InGaAsP/InP passive waveguides
Saeidi, Shayan; Rasekh, Payman; Awan, Kashif M.; Tugen, Alperen; Huttunen, Mikko J.; Dolgaleva, Ksenia (Elsevier BV, 2018-10-01)
We report on the study of the third-order nonlinear optical interactions in InxGa1-xAsyP1-y/InP strip-loaded waveguides. The material composition and waveguide structures were optimized for enhanced nonlinear optical interactions. We performed self-phase modulation, four-wave mixing and nonlinear absorption measurements at the pump wavelength 1568 nm in our waveguides. The nonlinear phase shift of up to 2.5 pi has been observed in self-phase modulation experiments. The measured value of the two-photon absor...
Properties of BaYO3 perovskite and hydrogen storage properties of BaYO3Hx
Gencer, Ayşenur; Surucu, Gokhan (Elsevier BV, 2020-03-27)
In this study, Density Functional Theory (DFT) calculations have been performed for BaYO3 perovskite with the generalized gradient approximation (GGA) as implemented in Vienna Ab-initio Simulation Package (VASP). The structural optimization of BaYO3 perovskite have been studied for the five possible phases: cubic, tetragonal, hexagonal, orthorhombic and rhombohedral to determine the most stable phase of BaYO3 perovskite. It has been found that the cubic phase is the most stable one and electronic and mechan...
Analytical solution and experimental verification of shaped charge jet penetration
Gozubuyuk, Serkan; Yıldırım, Raif Orhan (2006-07-07)
In the scope of this study a one dimensional shape charge code was developed using analytical and semi-empirical approaches. The penetration part of the code is based on the hydrodynamic theory of penetration. The code is capable of modeling and visualizing of shaped charge liner collapse, jet formation and target penetration. Factors affecting the penetration were investigated by utilizing the developed code. Since the code is based on the solution of some analytical expressions rather than the solution of...
Investigation of nanoantennas using surface integral equations and the multilevel fast multipole algorithm
Karaosmanoglu, Barıscan; Gur, Ugur Merıc; Ergül, Özgür Salih (2015-07-09)
A rigorous analysis of nanoantennas using surface integral equations and the multilevel fast multipole algorithm (MLFMA) is presented. Plasmonic properties of materials at optical frequencies are considered by using the Lorentz-Drude models and employing surface formulations for penetrable objects. The electric and magnetic current combined-field integral equation is preferred for fast and accurate solutions, which are further accelerated by an MLFMA implementation that is modified for plasmonic structures....
Citation Formats
N. Nayir, “Investigation of InP and SiGe nanomaterials via molecular dynamics simulations,” Ph.D. - Doctoral Program, Middle East Technical University, 2018.