Bulletin of the American Physical Society
APS March Meeting 2019
Volume 64, Number 2
Monday–Friday, March 4–8, 2019; Boston, Massachusetts
Session C31: DFT, Embedding, and, Beyond (ES1)Focus

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Sponsoring Units: DCP Chair: Timothy Berkelbach, University of Chicago Room: BCEC 203 
Monday, March 4, 2019 2:30PM  3:06PM 
C31.00001: Projectionbased quantum embedding for periodic systems Invited Speaker: Jason Goodpaster Quantum embedding methods are ideal for describing surface chemistry of large periodic systems by using a higher level of theory—such as wave function (WF) theory—for the smaller active site, while still accounting for the quantum mechanical interactions with the electrons in the surrounding environment with a more computationally tractable level of theory such as density functional theory (DFT). We have developed a projectionbased quantum embedding approach for the embedding of periodic systems that is numerically exact compared to KohnSham DFT. Furthermore, we show that our method can accurately and efficiently reproduce adsorption and reaction energies from canonical WF methods and experiments. 
Monday, March 4, 2019 3:06PM  3:18PM 
C31.00002: Density Matrix Embedding Theory for Strongly Correlated Solids Hung Pham, Laura Gagliardi Density matrix embedding theory (DMET) [Phys. Rev. Lett. 2012, 109, 186404] has offered a promising wave functioninwave function embedding method to treat electron correlation for large and extended systems. DMET has been gaining some successes for several lattice models and molecular systems. Herein, we present an extension of DMET to treat strongly correlated periodic systems, namely pDMET. In our implementation, a unit cell is considered as an impurity embedded in the environment made up by other unit cells in the computational supercell. The Wannier functions, i.e. the realspace presentation of the wave function, are used to perform the embedding calculation. The correlation potential is augmented in the kspace oneelectron Hamiltonian to selfconsistently minimize the difference between the oneelectron density matrix at the meanfield level and that at the highlevel. We test our method using different quantum chemical solvers (e.g. FCI, DMRGCI, CCSD) on variety of systems, such as onedimensional structure (hydrogen chain), covalent crystal (crystalline silicon), and ionic crystal (magnesium oxide). Finally, we discuss the feasibility of extending the method to compute electronic band structures of materials. 
Monday, March 4, 2019 3:18PM  3:30PM 
C31.00003: Embedded cluster density approximation for exchangecorrelation energy: a natural extension of the local density approximation Chen Huang We developed a local correlation method in the framework of KohnSham density functional theory (KSDFT). The method is termed embedded cluster density approximation (ECDA) and is a logical extension of the local density approximation. In ECDA, an embedded cluster is defined for each atom based on the finitetemperature densityfunctional embedding theory. The clusters' XC energy densities are calculated using highlevel XC functionals. The system's XC energy is then constructed by patching these locally computed, highlevel XC energy densities in the system in an atombyatom manner. A key result is the derivation of the relationship between the embedding potential and system's KS potential, based on which we show how to efficiently compute the system's XC potential following the optimized effective potential procedure. The accuracy of ECDA is examined by patching the exact exchange (EXX) and the random phase approximation (RPA) correlation energies in a onedimensional hydrogen chain, as well as by patching EXX energies in several molecules. We expect ECDA to be a simple, yet effective method to scale up highlevel KSDFT calculations in largescale strongly correlated systems. 
Monday, March 4, 2019 3:30PM  3:42PM 
C31.00004: Polaron Modulated Electronic Structures of Doped La_{2}CuO_{4} by SelfInteraction Corrected Density Funcional Theory Approach Qiushi Yao, Qihang Liu Singleparticle abinitio approaches, e.g., density functional theory (DFT) with standard exchangecorrelation functionals, is notorious for its poor treatment of the electronic structures of cuprate superconductors, not to mention their properties upon doping. Here, taking La_{2}CuO_{4} (LCO) as an exemplar, with both T and T’ phase, we show that selfinteraction corrected DFT accurately produces the experimentally observed insulator to metal transition, as a function of hole and electron doping concentration, respectively. Based on our calculations, doped carriers form localized polarons under low doping concentration dissolving into extended states upon high doping concentration, thus making the system conducting. The correct description of LCO provides us a practical route to the doping problems of strong correlated materials within KohnSham DFT framework, which is capable to treat a larger supercell than the methods beyond DFT. 
Monday, March 4, 2019 3:42PM  3:54PM 
C31.00005: Headtohead comparison of spectral properties of transitionmetal oxides using DFT and
beyondDFT methods Subhasish Mandal, G.L. Pascut, Kristjan Haule, Karin Rabe, David Vanderbilt The development of computational tools for the accurate prediction of the electronic structure of strongly correlated materials has been an active field of research for several decades. As a result, a variety of methods, including density functional theory (DFT), DFT+U, hybrid functionals, metaGGAs, GW quasiparticle approaches, and DFTembedded dynamical mean field theory (DMFT), are now available. Among these, the beyondDFT methods have been instrumental for understanding the electronic structure of strongly correlated systems, but it is unclear how reliable are those methods when applied to typical strongly correlated solids. It is thus of pressing interest to compare the quality of these methods as they apply to different categories of materials. Here we begin by systematically testing these methods on transitionmetal oxides (TMOs) such as FeO, CoO, MnO, and NiO, which provide a suitable platform since conventional DFT methods are known to fail to predict their electronic structure accurately. We present a headtohead comparison of spectral properties as obtained using the listed methods, and compare with experimental photoemission data where available. 
Monday, March 4, 2019 3:54PM  4:06PM 
C31.00006: Bridging molecular dynamics and correlated wavefunction methods for accurate finitetemperature properties Dario Rocca, Anant Dixit, Michael Badawi, Sébastien Lebègue, Tim Gould, Tomáš Bučko We introduce the ``selPT'' perturbative approach, based on ab initio molecular dynamics (AIMD), for computing accurate finitetemperature properties by efficiently using correlated wavefunction methods. We demonstrate the power of the method by computing a prototypical molecular enthalpy of adsorption in zeolite (CH_{4} on protonated chabazite at 300 K) using the random phase approximation. Results are in excellent agreement with experiment. The improved accuracy provided by selPT represents a crucial step towards the goal of truly quantitative AIMD prediction of experimental observables at finite temperature. 
Monday, March 4, 2019 4:06PM  4:18PM 
C31.00007: Towards a molecularlevel understanding of metallike conductivity in bacterial protein nanowires Peter Dahl, Atanu Acharya, Sibel Ebru Yalcin, Sophia Yi, J. Patrick O'brien, Victor Batista, Nikhil Malvankar Protein appendages of Geobacter sulfurreducens exhibit metallike conductivity and transport electrons at rates rivaling to those of metallic carbon nanotubes. Our recent experiments have revealed an increase in πstacking upon lowering the pH of nanowires leading to a 100fold increase in conductivity and carrier density. We employed molecular dynamics simulations to obtain a molecularlevel understanding of the enhanced πstacking obtained under highly acidic pH. Electronic structure calculations were also performed using QM/MM technique to elucidate the frontier orbitals and the energy gap between them. Our MD simulations suggest that under highly acidic pH significant structural rearrangement of the protein structure leads to the enhanced πstacking. Electronic structure calculation reveals that the enhanced πstacking results in higher coupling between the carrier states. Hence, conductivity is increases by several fold at highly acidic pH. Our results suggest that significant orbital overlap between adjacent charge carriers is pivotal in the observed conductivity of these nanowires. 
Monday, March 4, 2019 4:18PM  4:54PM 
C31.00008: A finitefield approach to performing GW calculations and solving the BetheSalpeter equation Invited Speaker: Giulia Galli We describe a finite field approach to compute density response functions, and to compute optical spectra and exciton binding energies of molecules and solids based on the solution of BetheSalpeter equation. The approach 
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