Bulletin of the American Physical Society
APS March Meeting 2020
Volume 65, Number 1
Monday–Friday, March 2–6, 2020; Denver, Colorado
Session M43: Computational Design and Discovery of Novel Materials IFocus
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Sponsoring Units: DCOMP DMP Chair: Feng Zhang, Ames Lab Room: 702 |
Wednesday, March 4, 2020 11:15AM - 11:51AM |
M43.00001: Computationally driven discovery of new borides in the ternary Li-Ni-B system Invited Speaker: Julia Zaikina The crystal structure prediction of multinary inorganic materials is a challenging task given the diversity of potential structures. Experimental validation of the computational predictions is a vital step for accelerated materials discovery, however solid state chemistry synthetic routes lack the predictability of the synthesis outcome. Yet, theoretical predictions of structure and thermodynamic stability of the new ternary phases can yield the desired roadmap for the targeted synthesis. On the other hand, efficient synthesis allows for the fast screening of compositional space, providing timely feedback for the iterative improvement of theoretical predictions. |
Wednesday, March 4, 2020 11:51AM - 12:03PM |
M43.00002: Corrosion-resistant magnesium alloy design based on the first-principles calculation Yaowei Wang, Tian Xie, Zhe Luo, Hong Zhu, Xiaoqin Zeng Second phase strengthening has been widely used in alloys designs, many of which however have been reported to enhance the galvanic corrosion of magnesium alloys. In this study, a semi-empirical model was proposed based on the first principles calculation to analyze the galvanic corrosion behaviour. Our model is validated in the case of Mg-Ge alloys, which is composed of anode Mg matrix and cathode Mg2Ge second phase. First principles calculations on the hydrogen evolution reaction upon Mg2Ge reveal that the rate-determining step is the hydrogen adsorption, which is extremely energetically unfavored but an inevitable intermediate state. The estimated exchange current of the hydrogen evolution upon Mg2Ge is about 3 orders of magnitude smaller than that on pure Mg, indicating the depressed galvanic corrosion of the Mg-Ge alloys is the result of the low hydrogen exchange current upon Mg2Ge. Moreover, some typical intermetallics, such as MgZn2 and MgSc, were selected to compare the corrosion properties of different Mg alloys, which is in close agreement with the experimental observations. Our model provides a promising perspective for designing better corrosion-resistant magnesium alloys. |
Wednesday, March 4, 2020 12:03PM - 12:15PM |
M43.00003: Automation of the first-principles calculation to search functional materials in high entropy alloys Hiori Kino, Tetsuya Fukushima, Toyohiro Chiyo The high entropy alloys attract much attention originally because of strength/hardness. They are potentially also useful as functional materials, such as high Curie temperature and high magnetic moment, and large spin-orbit coupling. However, the difficulty of the research of the high entropy alloys is that there exist too huge number of possibilities for humans to handle. Therefore, it is wise and inevitable to screen materials that have high functionality in the first-principles before executing experiments. |
Wednesday, March 4, 2020 12:15PM - 12:27PM |
M43.00004: Route to Room-temperature Superconductivity in Ternary Hydrides at Extreme Pressures Ying Sun, Jian Lv, Yu Xie, Hanyu Liu, Yanming Ma The recent theory-orientated discovery of record high-temperature superconductivity (Tc ~250 K) in sodalitelike clathrate LaH10 [1-4] is an important advance toward room-temperature superconductors. Here, we identify an alternative clathrate structure in ternary Li2MgH16 with a remarkably high estimated Tc of ~473 K at 250 GPa, which may allow us to obtain room-temperature or even higher-temperature superconductivity. The ternary compound mimics a Li- or electron-doped binary hydride of MgH16. The parent hydride contains H2 molecules and is not a good superconductor. The extra electrons introduced break up the H2 molecules, increasing the amount of atomic hydrogen compared with the parent hydride, which is necessary for stabilizing the clathrate structure or other high-Tc structures. Our results provide a viable strategy for tuning the superconductivity of hydrogen-rich hydrides by donating electrons to hydrides via metal doping. Our approach may pave the way for finding high-Tc superconductors in a variety of ternary or quaternary hydrides. |
Wednesday, March 4, 2020 12:27PM - 12:39PM |
M43.00005: Material design of indium iodine compounds Chang-Jong Kang, Gabriel Kotliar We apply material design methodology and find a new indium iodine compound, CsInI3, which is thermodynamically stable but is not reported in Inorganic Crystal Structure Database (ICSD) yet. By using the ab initio evolutionary algorithm, we find several meta-stable structures of CsInI3 and investigate their physical properties. The ideal cubic perovskite structure, which is one of the meta-stable phases, shows the structural instability of the iodine breathing mode at zero temperature. However, the cubic perovskite is eventually stabilized at finite temperature due to the contribution of the phonon entropy. The cubic perovskite shows band inversion above the Fermi level, indicating that it is a topological material. Other meta-stable structures are derived from the cubic perovskite and have two different sizes of indium octahedrons, thereby presenting bond and charge disproportionation. The new compound of CsInI3 presents diverse physics including bond and charge disproportionation, topological nature, and a possible application for photovoltaics, thereby providing an ideal playground for these research fields. |
Wednesday, March 4, 2020 12:39PM - 12:51PM |
M43.00006: A MoON Race: Computational Design of a Heteroanionic Metal-Insulator Transition Compound Molybdenum Oxynitride. Lauren Walters, Nathan J Szymanski, Danilo Puggioni, James Rondinelli Using symmetry principles and electronic structure calculations we designed a novel metal-insulator transition (MIT) compound MoON. The alpha and beta phase of this material were identified from a set of prototype AB2 structures based upon energetics, band gap, and the c/a ratio. We show that the fac ordering of the polyhedra are important for charge localization, singlet formation, and opening of the band gap. Our density functional calculations show how changes in the electronic band gap are driven by structural distortions, including 1D chain canting and dimer formation. Last we draw parallels between MoON and the well-studied VO2, demonstrating that properties such as the c/a lattice parameter ratio could be used for further design and identification of other rutile MIT materials. |
Wednesday, March 4, 2020 12:51PM - 1:03PM |
M43.00007: From materials discovery to solar cells: LaYS3 as a product of the computation/experiment loop Andrea Crovetto, Rasmus Nielsen, Mohnish Pandey, Karsten Wedel Jacobsen, Ole Hansen, Brian Seger, Ib Chorkendorff, Peter Vesborg One of the current key challenges in solar photovoltaics and solar-driven water splitting is to identify an efficient, stable, and inexpensive material to be used as a high-band gap (1.6-2.0 eV) absorber in tandem devices. With this purpose in mind, we have computationally screened 705 sulfide perovskites (ABS3). Only 15 compounds pass all the screening rounds, which include criteria such as phase stability, suitable band gap, low effective mass, and defect tolerance. The list of 15 compounds includes a number of materials that have not yet been reported experimentally. We have therefore attempted to synthesize some of those novel ABS3 compounds. Among them, LaYS3 was experimentally confirmed as a stable and especially attractive high-band gap photoabsorber [1], and it was possible to fabricate some prototype LaYS3 solar cells [2]. |
Wednesday, March 4, 2020 1:03PM - 1:15PM |
M43.00008: Ab initio prediction of Metal Organic Frameworks James Darby, Mihails Arhangelskis, Athanassios Katsenis, Joseph Marrett, Tomislav Friščić, Andrew J Morris First-principles crystal structure prediction is a well established technique which is routinely used across a diverse range of systems such as periodic solids, interfaces, and encapsulated nanowires. Here we present the first example of ab initio prediction of a Metal-Organic Framework (MOF). |
Wednesday, March 4, 2020 1:15PM - 1:27PM |
M43.00009: Predicting the phase stability of high entropy oxides Krishna Chaitanya Pitike, Craig A. Bridges, Jiang Bo, Katharine L. Page, Valentino Cooper High entropy, multicomponent systems are interesting due to the role that cation disorder may play in defining their mechanical, magnetic, reversible energy storage properties, etc. Within the class of high entropy oxides; rocksalt, fluorite, spinel and perovskite phases have all been recently synthesized. Complementing these endeavors, the current work explores a method for calculating the stability of high entropy oxides – compounds in which one cation-site is randomly and equally occupied by five chemical species – through a collaborative computational and experimental efforts. We construct a nearest neighbor (NN) model from enthalpies of mixing of end member oxides and binary oxide mixtures – in their respective potential stable phases – estimated through DFT calculations. The candidates for the high entropy oxides are predicted from the configurational landscapes of the five component oxides, estimated through Monte Carlo simulations using the NN model. Our approach allows us to evaluate potential impurity phases thereby making realistic predictions of novel multicomponent oxides that can be synthesized. |
Wednesday, March 4, 2020 1:27PM - 1:39PM |
M43.00010: Theoretical and computational methods for accelerated materials discovery Nikolai A Zarkevich, Duane D Johnson Predicting properties of materials and phase transformation using theoretical and computational multi-scale methods involving artificial intelligence and machine learning is important and highly rewarding. We investigate reliability of the relevant methods, apply them to caloric materials and high-entropy alloys, and demonstrate how theoretical guidance for experiment accelerates materials discovery. |
Wednesday, March 4, 2020 1:39PM - 1:51PM |
M43.00011: Stabilities and electronic structures of XYZ2 thermoelectric materials Liu Ke, Cai Xiaomeng, Hong Zhu A new class of high-performance thermoelectric materials XYZ2 has been revealed based on high-throughput simulations. But they could also have multiple phase transformations similar to many other high-performance thermoelectric materials like PbTe. Thus, it's important to study the stability and electronic structure of different phases, and how these are related to the chemistry of the compound. The phase stabilities have been assessed by support vector machine methodology. We find compounds with larger X ionic radius have P3m1 space group with X ion in octahedral interstices, while smaller X ionic radius favors a tetrahedral site occupation with a space group of the compound of I-42d. Based on the gradient boosting algorithm, density of states effective mass mS* and fermi surface complexity factor NV*K* are identified as important descriptors to enhance zT values. Compounds with larger mS* have a flat band to enhance Seebeck coefficient if the X-s (Y-d) orbitals have similar energy with Z-p orbital near the VBM. Cu and Ag based compounds with P3m1 space group are benefited from the Y-d orbital contribution to the high NV*K*. These results demonstrate altering ionic size and molecular orbitals may be used in strategies to improve the thermoelectric performance of XYZ2 compounds. |
Wednesday, March 4, 2020 1:51PM - 2:03PM |
M43.00012: The analytic metric for geometric series diffraction from icosahedral quasicrystals Antony Bourdillon Sharp diffraction patterns show long range order {1] in i-Al6Mn; translational symmetry is seen—by phase-contrast, optimum-defocus imaging—to be hierarchic. The icosahedral diffraction pattern was novel in two ways: that it included five-fold symmetric axes; having moreover diffraction orders in geometric series, imprecisely called Fibonacci. The orders differ from Bragg diffraction which is linear. How does a plane wave X-ray, or electron beam, scatter off the hierarchic structure? The diffraction angles due to scattering from the quasiperiodic solid diverge from Bragg conditions: quasi-Bragg angles are derived from quasi-structure factors with a metric that is derived numerically and analytically. The metric is a conversion factor, 1/(tau-0.5), where tau is the golden section: the metric harmonizes the incident sine wave with hierarchic scattering (all atoms scatter) while the response occurs in geometric series. The hierarchic structure is represented by triads of golden rectangles, each having principal planes, separated by spaces in geometric series, like the diffraction pattern [2]. [1] Shechtman, D, et al. (1984) Phys. Rev. Lett. 53, 1951, http://dx.doi.org/10.1103/PhysRevLett.53.1951 [2] A.J.Bourdillon, A.J., J. Mod. Phys. 10 [6] 624 (2019), DOI: 10.4263/jmp.2019.106044 |
Wednesday, March 4, 2020 2:03PM - 2:15PM |
M43.00013: Elucidating the role of anharmonic effects in understanding oxidation of methane Preeti Bhumla, Saswata Bhattacharya
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