Bulletin of the American Physical Society
Joint Fall 2021 Meeting of the Texas Sections of APS, AAPT, and SPS
Volume 66, Number 10
Thursday–Saturday, October 21–23, 2021; Houston; Central Time
Session M02: Condensed Matter, Plasma Physics & Computational Physics II |
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Chair: Donna Stokes, UH Room: STEM 2103 |
Friday, October 22, 2021 2:00PM - 2:36PM |
M02.00001: MHD Turbulence and the Geodynamo Invited Speaker: John Sheblalin The outer core of the Earth contains a turbulent magnetofluid that is the source of the geomagnetic field. Magnetohydrodynamic (MHD) turbulence, per se, contains a dynamo mechanism that creates and maintains the geomagnetic field. This ‘geodynamo’ can be understood in terms of the statistical mechanics of rotating MHD turbulence. Here, we describe a mathematical model of the outer core, review theoretical and numerical results associated with it, explain the origin of the energetic, quasi-stationary geomagnetic dipole and thus present a solution to the ‘dynamo problem.’ [Preview Abstract] |
Friday, October 22, 2021 2:36PM - 2:48PM |
M02.00002: ParaMonte: A Powerful Serial/Parallel Monte Carlo and MCMC Library for Python, MATLAB, R, Fortran, C$++$, and C Joshua Osborne, Parvat Sapkota, Shashank Kumbhare, Fatemeh Bagheri, Amir Shahmoradi Predictive science is a multilevel process requiring observational data and a model/hypothesis which will have to be calibrated and validated to eventually predict the quantity of interest. The primary method for model calibrations has, for decades, been that of Monte Carlo simulations. Here we present and discuss a collection of popular and powerful Monte Carlo techniques that can aid inference and uncertainty quantification in Machine learning and Bayesian problems that have both serial and parallel implementations within our package, ParaMonte. The primary focus in the development of ParaMonte has been on user-friendliness, accessibility from multiple programming languages and platforms, high-performance, parallelism and scalability, as well as reproducibility and comprehensive post-processing and visualization of the simulation results. Users can simply pass a user-made objective function to the samplers and upon completion, a series of files will be generated for comprehensive-reporting and post-processing of each simulation and its results. Automatic restart functionality is the core feature of all ParaMonte samplers and simulations. The ParaMonte library is permanently located at https://github.com/cdslaborg/paramonte. [Preview Abstract] |
Friday, October 22, 2021 2:48PM - 3:00PM |
M02.00003: Entanglement Swapping in the Virtual Quantum Optics Laboratory Courtney Hodgson, Aishi Guha Entanglement is a form of superposition that occurs when two photons are emitted from a spontaneous parametric down-conversion (SPDC) entanglement source. Entanglement enables various quantum applications, such as teleportation and complex encryption. Entanglement swapping is the teleportation of entangled photons without interaction. In this experiment, we perform entanglement swapping by utilizing the online virtual quantum optics lab (VQOL), which is based on a classical model of quantum optics. We use two SPDCs to send two pairs of entangled photons to six detectors. Two of the detectors are paired with a beam splitter, and two polarizing filters perform a check of a successful Bell State Measurement (BSM), while the other four detectors paired with varying polarizing beam splitters perform Quantum State Tomography (QST). To optimize for fidelity, we vary the dark counts on the detectors. We achieve a maximum average fidelity of 0.69 $\pm$ 0.02 with a detector dark count rate of 5/s, demonstrating entanglement swapping with two SPCD sources. Our results explore how effective a classical simulation, such as VQOL, is at closely modeling a quantum experiment, i.e. entanglement swapping. [Preview Abstract] |
Friday, October 22, 2021 3:00PM - 3:12PM |
M02.00004: Effects of hydrogen passivation and dipole corrections on density functional theory calculations of supercell-slab models for GaN on diamond interfaces Eric Welch, Luisa Scolfaro Zinc blende GaN is a heteropolar structure with a non-zero dipole moment that effects the charge density and built-in potential across GaN-semiconductor interfaces. Results are shown here from a hybrid density functional theory study of zinc blende GaN and zinc blende diamond using the supercell slab model; GaN on diamond is a promising interface in high electron mobility transistor applications. Electronic structure calculations show that a type I interface (with a Ga adlayer) between GaN and diamond is stable with an adhesion energy of 0.704 eV/A$^{\mathrm{2}}$ (4.346 J/m$^{\mathrm{2}})$. Projecting the density of states onto each supercell layer shows that the diamond charge density intercalates into the first layer of GaN, agreeing with recent experiments. It is shown that pseudo-hydrogen passivation of dangling bonds and dipole corrections, used to account for heteropolar structures of GaN, along with the inclusion of a Ga adlayer work to remove spurious interactions between periodic supercell images and yield energetic results like more complicated structural models e.g., wedge-shaped supercells. [Preview Abstract] |
Friday, October 22, 2021 3:12PM - 3:24PM |
M02.00005: Lead-free All-perovskite Tandem Solar Cell Arman Duha, Mario Borunda We simulated a lead-free all-perovskite tandem solar cell using the SCAPS-1D simulation tool. The purpose of this work is to assess the performance of alternatives to lead-based perovskite in a tandem structure. First, the top and bottom subcells, consisting of MAGeI$_3$, and FASnI$_3$, respectively, were optimized individually by varying material properties such as thickness, electron affinity, and capture cross-section. These standalone optimized subcells are then utilized for the tandem structure. The final tandem cell thickness was determined based on short circuit current density (J$_{\text{SC}}$) matching of the standalone subcells by means of varying the thickness of the subcells. A matching J$_{\text{SC}}$ of 14.75 mA/cm$^2$ was obtained for the top and bottom subcell thickness of 970 nm and 1400 nm, respectively. At this current matching condition, the tandem cell yielded a very high open-circuit voltage (V$_{\text{OC}}$) of 2.63 V, resulting in an efficiency of 30.89\% which is significantly higher than that of the single junction. [Preview Abstract] |
Friday, October 22, 2021 3:24PM - 3:36PM |
M02.00006: Stability and Optical Properties of Copper-Cysteamine with Halogens by First Principles Calculations Noura Alkhaldi, Muhammad N. Huda Copper cysteamine (Cu-Cy) is known as a photosensitizer that can be activated by visible light, X-rays, microwaves, and ultrasound to generate reactive oxygen species (ROS). ROS which are produced by Cu-Cy can be used to treat the cancer, infection diseases as well to decontaminate the water from the microbes, and organic dye molecules. Hence, it is important to understand the electronic and optical properties of Cu-Cy material. In this presentation, we will show results from our density functional theory (DFT) calculations of the stability of Cu-Cy structures as well the electronic and optical properties of Cu-Cy-X (X$=$ F, Cl, Br, I). Different spin-multiplicities as well spin-orbit-coupling (SOC) are considered to understand the electron transition from the occupied to the unoccupied bands. Defects such as Cu-vacancy and X-vacancy are made in the pristine structures of Cu-Cy-X to see how those affect the stability of the structures. Reaction barriers of Cu atom in Cu-Cy-X are calculated to mimic the Cu leaching which are observed experimentally. Our theoretical results show good agreements with the experimental data. [Preview Abstract] |
Friday, October 22, 2021 3:36PM - 3:48PM |
M02.00007: Electronic and Magnetic Properties of Silicon-Carbide Fullerenes-like Nanostructures. Hussain Alathlawi, Muhammad Huda Silicon carbide (SiC) is an important material for extreme environment applications, such as high temperature, high pressure, high power, etc. In its bulk phase, it has more than 200 polymorphs. At the nanoscale, stabilized functional clusters are of particular interest. Experimentally, the C$_{60}$ fullerene was found to be the most stable form of carbon. On the other hand, Si and C have similar valence electrons configurations, implying that Si and SiC could form similar fullerene structures. We will present our first-principles investigations of the Si$_{30}$C$_{30}$ fullerene-derived clusters. The calculation started from the Si$_{60}$ fullerene; we studied different configurations of Si$_{30}$C$_{30}$ fullerene-like structures and relaxed them without any symmetry. The result has shown some Si-C and Si-Si double bonds in unpassivated structures. Also, the endohedral doping of fullerene with W atom and the clusters' magnetic properties will be presented. In addition, we choose the most spherical structure, with a high number of Si-C bonds, to show the magnetic properties for the endohedral doping of transition metal atoms (W, Ta, Fe, Nb, Hf). Finally, stabilities of these clusters' will be discussed. [Preview Abstract] |
Friday, October 22, 2021 3:48PM - 4:00PM |
M02.00008: Explaining the Properties of Plutonium with DFT Achyuth Manoj, Sarah Hernandez, Muhammad Huda Plutonium, with atomic number 94, is a strongly correlated electron system, with the electronic configuration of Pu atom being Rn 5f6 7s2, making it a difficult material to perform theoretical calculations with. Plutonium is not a well understood element, and it shows anomalous properties, including but not limited to, showing six allotropic phases in its metallic state, with the ground state structure being a low symmetry monoclinic structure. With increased temperature, the structure changes to higher symmetry allotropes before melting. We use DFT (density functionals theory) implemented in the plane wave code VASP (Vienna Ab initio Simulation Package) to perform theoretical calculations on the allotropes of Plutonium to understand its properties. We use the GGA (generalized gradient approximation) functional in DFT to perform our calculations, and then include spin orbit coupling effects. We compare theoretical volume per atom to experimental values. Including spin orbit coupling effects gives us a better prediction for volume. Our DFT calculations predict that the lower temperature phases are nonmagnetic while the higher temperature phases are antiferromagnetic. [Preview Abstract] |
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