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.


Investigation of effect of design and operating parameters on acoustophoretic particle separation via 3D device-level simulations
Sahin, Mehmet Akif; ÇETİN, BARBAROS; Özer, Mehmet Bülent (Springer Science and Business Media LLC, 2019-12-16)
In the present study, a 3D device-level numerical model is implemented via finite element method to assess the effects of design and operating parameters on the separation performance of a microscale acoustofluidic device. Elastodynamic equations together with electromechanical coupling at the piezoelectric actuators for the stress field within the solid parts, Helmholtz equation for the acoustic field within fluid, and Navier-Stokes equations for the fluid flow are coupled for the simulations. Once the zer...
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...
Analysis of composite nanoparticles with surface integral equations and the multilevel fast multipole algorithm
Ergül, Özgür Salih (IOP Publishing, 2012-06-01)
Composite nanoparticles involving multiple parts with different material properties are analyzed rigorously with surface integral equations and the multilevel fast multipole algorithm. Accuracy and efficiency of the developed parallel implementation are demonstrated on spherical objects with dielectric, perfectly conducting, plasmonic, and double-negative regions. Significant effects of the formulation on numerical solutions are also considered to show the tradeoff between the efficiency and accuracy.
Lattice dynamical and thermo-elastic properties of M2AlB (M = V, Nb, Ta) MAX phase borides
Surucu, Gokhan; Gencer, Ayşenur; Wang, Xiaotian; Surucu, Ozge (Elsevier BV, 2020-04-05)
The structural, electronic, dynamic, and thermo-elastic properties of M2AlB (X = V, Nb, Ta) MAX phase borides were investigated using first principle calculations as implemented in the Vienna Ab-initio Simulation Package (VASP) with the generalized gradient approximation (GGA). The obtained structural properties and formation energies showed the thermodynamic stability and synthesizability of M2AlB. The electronic band structures were determined and they revealed that these compounds had a metallic characte...
Tuerker, Lemi; Atalar, Taner; Guemues, Selcuk (Informa UK Limited, 2009-01-01)
Computational studies on tetranitro derivatives of [2,2]paracyclophane are carried out at B3LYP/6-31G(d,p) level of theory. Optimized geometries, electronic structures and some thermodynamic properties have been obtained in their ground states. Also, detonation performances were evaluated by the Kamlet-Jacobs equations, based on the quantum-chemical calculated densities and heat of formation values. Aromaticities were investigated by performing NICS (nucleus independent chemical shift) calculations using th...
Citation Formats
N. Nayir, “Investigation of InP and SiGe nanomaterials via molecular dynamics simulations,” Ph.D. - Doctoral Program, Middle East Technical University, 2018.