Bulletin of the American Physical Society
APS March Meeting 2019
Volume 64, Number 2
Monday–Friday, March 4–8, 2019; Boston, Massachusetts
Session L31: Electronic Structure of Quantum Systems IIFocus
|
Hide Abstracts |
Sponsoring Units: DCP Chair: Koblar Jackson Room: BCEC 203 |
Wednesday, March 6, 2019 11:15AM - 11:51AM |
L31.00001: Room-Temperature Magnetoresistance in Single-Molecule Devices Invited Speaker: Eliseo Ruiz The goal of this communication is to present a well-defined experimental/theoretical route map to reach single-molecule devices based on porphyrin systems showing magnetoresistance at room temperature. We have already reported that STM measurements of deposited metal tiocyanate (and selenocyanate) complexes on heavy metal surfaces that have large spin-orbit contributions allows to detect magnetoresistance.[1,2] Such magnetoresistance effect is similar to that reported by Fert and Grünberg in magnetic metal layers used in hard disk heads, just the inversion of the magnetization of the magnetic tip results in an important change in the transport properties of the device and more recently, in magnetic RAM memories as STT-MRAM devices. |
Wednesday, March 6, 2019 11:51AM - 12:03PM |
L31.00002: Problems in the treatment of transition metal magnetism with the SCAN meta-GGA functional David Singh, Yuhao Fu We test the SCAN functional for magnetic transition metals including Fe, Co and Ni and the near magnetic elements, V and Pd. We find that while SCAN modestly enhances magnetic moments it very strongly enhances magnetic energies leading to qualitatively incorrect predictions for technologically important systems including steel. The origin of these large errors is discussed. |
Wednesday, March 6, 2019 12:03PM - 12:15PM |
L31.00003: The calculation of accurate core electron binding energy shifts and absolute core electron binding energies using the SCAN exchange-correlation functional Juhan Matthias Kahk, Johannes Lischner Core electron X-ray Photoelectron Spectroscopy (XPS) is often used to characterize the elemental as well as the chemical composition of surfaces. However, as experimental practice moves towards the study of increasingly complex systems, the analysis of recorded spectra becomes ever more challenging. First principles calculations of core electron binding energies can substantially alleviate the problems that are commonly encountered in “peak assignment”. |
Wednesday, March 6, 2019 12:15PM - 12:27PM |
L31.00004: A new generation of effective core potentials from correlated calculations: 3rd row main group Guangming Wang, Abdulgani Annaberdiyev, Cody Melton, Michael Bennett, Lubos Mitas Recently, we have developed a new generation of effective core potentials (ECP) using valence energy isospectrality with explicitly correlated all-electron excitations and norm-conservation criteria. We extend our correlation consistent effective core potentials (ccECP) to 3rd row main group elements. For K and Ca, we use a Ne core and for the 4p elements we utilize large core potentials with 3d-electrons included in the core and with 4s and 4p in the valence shell. We also incorporate relativity including averaged spin-orbit effects. Our ccECPs reproduce all-electron spectra within about chemical accuracy ≈ 0.05 eV. The transferability of ccECPs is tested on corresponding monohydride and monoxide molecules in a wide range of binding geometries. The ccECPs include also optimized valence basis sets and additional comparisons with previously constructed ECPs. |
Wednesday, March 6, 2019 12:27PM - 12:39PM |
L31.00005: Schrödinger-Pauli Theory of Electrons: New Perspectives Viraht Sahni The Schrödinger-Pauli (SP) equation corresponds to a system of |
Wednesday, March 6, 2019 12:39PM - 12:51PM |
L31.00006: Local embedding/downfolding auxiliary-field quantum Monte Carlo (AFQMC) Brandon Eskridge, Henry Krakauer, Shiwei Zhang A local embedding and effective downfolding scheme has been developed and implemented in the auxiliary-field quantum Monte Carlo (AFQMC) method (Shiwei Zhang and Henry Krakauer, Phys. Rev. Lett. 90, 136401 (2003)). Local embedding in the occupied space (Yudis Virgus, Wirawan Purwanto, Henry Krakauer, and Shiwei Zhang, Phys. Rev. Lett. 113, 175502 (2014)) and local effective downfolding in the virtual space are employed to treat strongly correlated local clusters with an effective Hamiltonian. The accuracy is controlled by two geometric cutoff parameters that define the occupied space embedding and virtual downfolding regions. The systematic cutoff dependence of relative energies of physical and chemical interest is found to converge rapidly to the full AFQMC treatment. Thus, significant computational savings is achieved while maintaining a high degree of accuracy. This significantly increases the system size which can be accurately treated with AFQMC. Applications to transition metal atoms in 1D and in graphitic environments are presented. (Shiwei Zhang also acknowledges the Center for Computational Quantum Physics, Flatiron Institute). |
Wednesday, March 6, 2019 12:51PM - 1:03PM |
L31.00007: Benchmark studies for adsorption bond energies to transition metal surfaces Manish Kothakonda, Jinliang Ning, Yubo Zhang, James Furness, Jianwei Sun The accurate prediction of adsorption energies for molecules on metal surfaces is a challenging subject in condensed matter physics, applied catalysis and physical chemistry research. The use of computational methods such as density functional theory (DFT) calculations to describe surface-adsorbate bond strength is increasing. Often these adsorption energies are used to study heterogeneous catalysis in thermal and electrochemical reactions. Here, we compare the structures and energetics for small gaseous molecules adsorbed to various transition-metal surfaces from density functionals with experimental results [1], with focus on MetaGGAs such as the strongly constrained and appropriately normed (SCAN) [2] density functional that recognizes the different chemical bonds. |
Wednesday, March 6, 2019 1:03PM - 1:15PM |
L31.00008: An exchange-correlation functional capturing bulk, surface, and confinement physics Attila Cangi, Francisca Sagredo, Ann E Mattsson We present the construction of an exchange-correlation functional which enables us to capture bulk, surface, and confinement physics with a single functional. Using the subsystem functional formalism[1,2,3] and the electron localization function, we interpolate between reference systems representing different physical regimes (homogeneous electron gas, the Airy gas, and the harmonic oscillator gas)[4,5]. The resulting functional can be viewed as a meta-GGA on the Jacob’s ladder classification scheme. We report on the initial assessment of this functional, as tested on various materials. |
Wednesday, March 6, 2019 1:15PM - 1:27PM |
L31.00009: A first- principles study of insulating La2CuO4and its transition to the metallic state with Sr-doping Kanun Pokharel, James Furness, Christopher Lane, Ruiqi Zhang, Bernardo Barbiellini, Yubo Zhang, Arun Bansil, Jianwei Sun, Robert Markiewicz Correct prediction of the electronic structure of La2CuO4(LCO), an exemplar half-filled cuprate, has been a long-standing problem where the commonly used exchange- correlation functionals fail to reproduce the experimentally observed insulating state. In contrast, Strongly-Constrained-and-Approximately-Normed (SCAN) functional properly captures not only the ground state antiferromagnetic insulator character of LCO but also its transition to metallic state with Sr doping. We compare and contrast our SCAN-based results with the corresponding results obtained using other meta-GGA’s and hybrid functionals. Our analysis suggests that the SCAN functional can provide a new pathway for first-principles modeling of cuprates and other correlated materials. |
Wednesday, March 6, 2019 1:27PM - 1:39PM |
L31.00010: The Wilson basis applied to electronic structure James Brown, James Whitfield We present a method to calculate electronic energies using a pruned phase-space grid of Wilson basis functions. Computational scaling of O(N8/3) is realized by representing the Coulomb potential in a sum-of-products form and calculating energies using iterative methods. Convergence of the Wilson basis is analyzed in detail for multiple states of H2 and He with and without a strong magnetic field. |
Follow Us |
Engage
Become an APS Member |
My APS
Renew Membership |
Information for |
About APSThe American Physical Society (APS) is a non-profit membership organization working to advance the knowledge of physics. |
© 2024 American Physical Society
| All rights reserved | Terms of Use
| Contact Us
Headquarters
1 Physics Ellipse, College Park, MD 20740-3844
(301) 209-3200
Editorial Office
100 Motor Pkwy, Suite 110, Hauppauge, NY 11788
(631) 591-4000
Office of Public Affairs
529 14th St NW, Suite 1050, Washington, D.C. 20045-2001
(202) 662-8700