Bulletin of the American Physical Society
APS March Meeting 2023
Volume 68, Number 3
Las Vegas, Nevada (March 5-10)
Virtual (March 20-22); Time Zone: Pacific Time
Session JJ10: V: Computational |
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Sponsoring Units: DMP Chair: Jorge Munoz, University of Texas at El Paso Room: Virtual Room 10 |
Monday, March 20, 2023 3:00PM - 3:12PM |
JJ10.00001: Accelerated Structure Prediction of Organic Molecular Crystals Ethan P Shapera, Dejan-Krešimir Bucar, Rohit Prasankumar, Christoph Heil Organic molecular solids form key components of many common goods including medicines, fertilizers, and paints. Organic molecular crystals have been proposed as high-performance semiconductors and optoelectronics. The properties of the organic molecular crystals depend strongly on both the choice of constituent molecules and the crystal structure. Controlling and predicting the crystal structure often proves to be a main impediment toward application. Current approaches to crystal structure prediction rely on generating large numbers of structures. This is computationally expensive because it often requires performing calculations on 10,000's or 100,000's of structures, most of which are not experimentally realizable. Here we accelerate the approach by constructing machine learning models to predict the properties of relaxed organic molecular crystal structures using only knowledge of the generated unrelaxed crystal structures. We demonstrate and validate our approach on organic salts formed from small ring molecules. The constructed models are able to both interpolate within the same chemical systems and provide limited extrapolative predictions to unseen chemical compositions. |
Monday, March 20, 2023 3:12PM - 3:24PM |
JJ10.00002: Asymmetric Transmission Control in Layered Natural Hyperbolic Crystals Reed Jones, Rair Macêdo, Robert E Camley Hyperbolic materials have been the focus of intense discussion of the past two decades due to their unprecedented ability to manipulate optical fields and the energy flow of light in very unusual and exciting ways1; making them excellent candidates for novel infrared detectors2 and light-harvesting devices3. More recently, the effect of the anisotropy direction with respect to the surface of the material has been shown to be a strong agent for controlling wave propagation4. Here, we investigate the electromagnetic properties of a structure composed of two optically active materials. Each material is a hyperbolic crystal whose anisotropy axis is rotated with respect to its surface. The rotation gives control of the transmission spectra to obtain two frequencies where at one frequency, light with positive incident angles is transmitted while it is absorbed for negative incident angles and the reverse occurs at a second frequency. This, in turn, can lead to tunable output collimated beams that are directional dependent even when light is incident at all angles (here we will show examples of this using a point source). From these discoveries, we expect that our structure can be applied as an efficient frequency or angle selector, demultiplexer or optical filter. |
Monday, March 20, 2023 3:24PM - 3:36PM |
JJ10.00003: Manipulating interlayer magnetic orders of 2D magnets by stacking rotation Liangbo Liang, Xiangru Kong, Hongkee Yoon, Myung Joon Han Chromium triiodide (CrI3), a two-dimensional (2D) van der Waals (vdW) magnet, exhibits complex magnetism depending on the number of layers and interlayer stacking patterns. Within each layer spins are ferromagnetically coupled with strong out-of-plane anisotropy, but between layers the magnetic orders can be manipulated between ferromagnetic (FM) and antiferromagnetic (AFM) by numerous ways due to the relatively weak interlayer coupling. In this talk, we considered three energetically stable stacking patterns R3, C2/m and AA in bilayer CrI3, and the reversed counterparts R3-r, C2/m-r and AA-r through rotating one layer by with respect to the other layer. Our first-principles calculations suggest that the interlayer magnetic ground state can be switched from AFM to FM (or FM to AFM) by reversing the stacking pattern, corroborating prior experimental results in bilayer CrBr3. Detailed microscopic analysis was carried out by magnetic force theory calculations on C2/m stacking which favors AFM and C2/m-r stacking which favors FM. The interlayer magnetic interactions and the origin of the magnetic order change were revealed through specific orbital analysis. Our work demonstrates that stacking rotation, like stacking translation, allows us to control and manipulate the interlayer magnetism of CrI3 and possibly other 2D magnetic materials as well. |
Monday, March 20, 2023 3:36PM - 3:48PM |
JJ10.00004: Interlayer Spin Transport in 2D Material Heterostructures with Arbitrary Epitaxies: A Computational Design from Bulk Properties Adam M Pfeifle, Marcelo A Kuroda Recently, magnetic tunnel junctions (MTJs) demonstrated in two-dimensional materials (2DMs) are promising for spin transport applications. The facile formation of 2DM-based junctions without epitaxial constraints of bulk MTJs demand quantitative transport descriptions to rapidly prescreen systems. Here we present a model based on the physical properties of bulk constituents, circumventing the computational burden of full quantum transport. Mechanisms governing transport in these heterostructures are determined from the electronic and complex band structures of individual 2DMs in their bulk form using density functional theory. We analyze the dependence of tunneling and magnetoresistance on various features such as effective tunneling rates, van der Waals gap, and binding energy. Importantly, our model can tackle systems with arbitrary epitaxies, which are usually intractable for first principles calculations. We discuss the cases where heterostructures are formed by either magnetic channels or magnetic leads, with emphasis given to Fe-dihalides which show tunneling magnetoresistance values of up to 10,000%. The good agreement between this model and full quantum transport calculations in heterostructures signals promising potential for the accelerated data-driven screening of 2DM candidates for use in spintronic applications. |
Monday, March 20, 2023 3:48PM - 4:00PM |
JJ10.00005: A First-Principles Study of Energetics of AsxP1-x alloys with A7 and A17 Symmetries Kazi Jannatul Tasnim, Md Rajib khan Musa, Ming Yu The most stable allotropes of Phosphorus (P) and Arsenic (As) are Black phosphorous (space group of A17 or -P) and Gray arsenic (space group of A7 or -As) respectively. The fact that, the conversion between and the phase can be possible, by alloying them with different compositions can lead to a structural transition followed by a phase coexistence between these two systems. Recently, we performed a first-principles calculation and systematically investigated the optimum geometry, electronic structure, and the effect of alloying in the structural transition of AsxP1-x alloys. A random substitution of P with As in -P results in black AsxP1-x alloys. Such systems were optimized within a full relaxation process allowing all atoms fully relaxed without any restriction on the lattice symmetry and the volume. Following the same procedure, AsxPx-1 alloys with A7 symmetry were also obtained by substituting As with P in -As. The calculated formation energy of AsxP1-x-alloys shows a cross over point at x = 0.25 and a co-existence in the range of x = 0.25 - 0.5, independent of the size of supercells chosen in the calculations. The low formation energy in As rich area implies that the AsxP1-x alloys with A7 symmetry are energetically more stable than AsxP1-x alloys with A17 symmetry. |
Monday, March 20, 2023 4:00PM - 4:12PM |
JJ10.00006: Studies of Effects of External Electric Field on Isolated and Crystalline Furan-derived Nanothread and PVDF through ReaxFF Method Tao Wang, Yawei Gao, Bo Chen, Vincent H Crespi, Adri C Van Duin Furan nanothreads have recently been synthesized through pressure-induced polymerization of molecular furan at room temperature. Its lower onset reaction pressure of about 10 GPa enables the scalability of synthesis and facilitates experimental measurements that require large quantity of samples. Furan threads promises to have intriguing electric properties owing to the polarity of the precursor coupled with a relatively rigid backbone. In order to investigate the response of external electric field applied on furan threads, we re-optimized the Chenoweth et al. C/H/O/ combustion ReaxFF reactive force field by extending the training set to include the thread oligomer bending property and the specific atomic net charge of furan thread. The reaction barrier of the furan dimer, and dipole moment of furan thread calculated using the re-trained force field agree well with that from DFT calculations. Comparing with an organic ferroelectric polymer with a flexible backbone, like a PVDF single chain, we find that isolated furan thread twists toward the electric field direction and generate larger torque with respect to the anchored end during to its rigid backbone. Both the randomly packed furan threads and PVDF can be poled by a moderate electric field at 50 K. These theoretical results predict unique physical responses for these novel furan threads which help inspire experimental measurement in the future. |
Monday, March 20, 2023 4:12PM - 4:24PM |
JJ10.00007: Looking for metallic states in novel exfoliable 1D materials Chiara Cignarella, Davide Campi, Nicola Marzari One-dimensional materials are extremely attractive due to their unique electronic properties and potential for next-generation applications. A high-throughput screening of experimental inorganic materials has provided a portfolio of more than 800 novel 1D/quasi-1D materials exfoliable from their 3D parent compound, out of which we select a dataset of metallic chains as possible candidates for vias and interconnects. Often, their low-dimensional nature leads to dynamical instabilities in the form of Peierls distortions or charge-density waves (CDW), which drive structural phase transitions. Here, we analyse the stability of these novel materials, identifying the reconstructed stable superstructures from the phonon instabilities. Several interesting behaviors emerge - from Peierls metal-insulator transitions to the emergence of Dirac cone semimetals. In order to get more insight into the mechanisms of the CDW, we investigate the nesting function and the critical role of the electron-phonon coupling, still largely unexplored in realistic quasi-1D systems. |
Monday, March 20, 2023 4:24PM - 4:36PM |
JJ10.00008: Building better cluster expansions on a basis-free foundation Paul E Lammert, Vincent H Crespi We develop the cluster expansion method, much used in study of configurationally-disordered materials, on a conceptually clarified and basis-free foundation. Practical benefits include freedom from an underdetermination problem to which the usual procedure is susceptible, and a correct extension to nonuniform configuration distributions. |
Monday, March 20, 2023 4:36PM - 4:48PM |
JJ10.00009: Energy landscape in Ni-Co-Cr and related alloys Nikolai A Zarkevich, Timothy M Smith, John W Lawson Among multi-principal element alloys, the NiCoCr middle-entropy alloy has an outstanding combination of strength and ductility at both low and elevated temperatures. Equiatomic NiCoCr is a single-phase alloy with the face centered cubic (fcc) crystal structure. A low stacking fault energy in the fcc matrix is a cause of a relatively low creep in this alloy. The hexagonal close-packed (hcp) structure differs from the fcc by a stacking of atomic layers. The energy difference between the hcp and fcc structures is known to correlate with the stacking fault energy in the fcc phase. We compute formation and relative structural energies versus composition in the Ni-Co-Cr ternary and related quaternary systems, discuss possibilities of compositional adjustments, and compare theoretical predictions with experiment. |
Monday, March 20, 2023 4:48PM - 5:00PM Author not Attending |
JJ10.00010: Quantum computing for computational materials design Maximilian Amsler, Johannes Selisko, Thomas Eckl The corporate research and advance engineering division at Bosch utilizes a variety of materials modeling methods to supplement expensive and time-consuming experimentation and prototyping with simulations on classical supercomputers, which ultimately leads to the development of improved products and services. At their core, many relevant applications involve strongly correlated materials which are often inaccurately described by conventional electronic structure methods such as density functional theory. The emerging field of quantum computing could potentially map models of such materials classes more efficiently and with higher accuracy compared to classical methods. Here, we use dynamical mean field theory in conjunction with a classical and a quantum impurity solver based on a hybrid quantum-classical approach for simulating strongly correlated materials. We present the results of our predictions for several real materials systems, and the challenges involved when constructing relevant subspace Hamiltonians German Federal Ministry of Education and Research (BMBF) under project No. 13N15574.. |
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