Bulletin of the American Physical Society
APS March Meeting 2021
Volume 66, Number 1
Monday–Friday, March 15–19, 2021; Virtual; Time Zone: Central Daylight Time, USA
Session J20: Density Functional Theory and Beyond IILive
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Sponsoring Units: DCOMP DCP DCMP DPOLY Chair: Can Ataca, University of Maryland, Baltimore County |
Tuesday, March 16, 2021 3:00PM - 3:12PM Live |
J20.00001: Absolutely Localized Open-shell WF-in-DFT Huzinaga Embedding Daniel Graham, Xuelan Wen, Dhabih Chulhai, Jason Goodpaster While density functional theory (DFT) is often seen as the go-to for quantum mechanical calculations on chemical systems, current implementations have several well known deficiencies. More robust wave function (WF) methods can provide higher accuracy, but that accuracy comes at a significant computational cost. Quantum embedding methods provide a strategy for performing highly accurate calculations on chemical systems while not incurring high computational cost. By dividing a system into absolutely localized subsystems -- described by only the basis functions of the subsystem atoms -- we can significantly reduce the overall computational cost. Huzinaga projection operator based absolute localization wavefunction embedded in DFT (WF-in-DFT) energy differences recreate those of full system WF results across a diverse test set. Recently, we have developed an open-shell embedding extension to the method which can recreate CCSD(T) transition metal spin-splitting energies to within 1 kcal/mol for a fraction of the computational cost. |
Tuesday, March 16, 2021 3:12PM - 3:24PM Live |
J20.00002: Accurate and numerically efficient r2SCAN meta-generalized gradient approximation James Furness, Aaron Kaplan, Jinliang Ning, John Perdew, Jianwei Sun There are two core goals in exchange-correlation functional design: accuracy and efficiency. Whilst modern semi-local functionals have greatly improved accuracy, this has often been at the cost of efficiency. In a recent publication [1] Bartók and Yates propose a regularised SCAN (rSCAN) that resolves these numerical problems for the SCAN functional [2] at the expense of breaking exact constraints and reducing accuracy. We present the r2SCAN functional [3] that restores exact constraint adherence while preserving regularisation. The r2SCAN functional combines the accuracy of SCAN with the numerical efficiency of rSCAN and presents a powerful tool for bringing high accuracy DFT to numerically sensitive and large-scale problems. |
Tuesday, March 16, 2021 3:24PM - 3:36PM Live |
J20.00003: Computation of Phonon-Mediated Resistivity in Sr2RuO4 from first principles Felix Antoine Goudreault, Samuel Ponce, Feliciano Giustino, Michel Cote Because of its strong structural similarities to some high-Tc cuprates, Sr2RuO4 (SRO), a supposedly correlated superconductor, has attracted a lot of attention recently. Even though the discovery of superconductivity in SRO happened more than 20 years ago, the nature of the superconducting gap symmetry is still debated today. SRO also bears other unconventional properties like a strong anisotropy of the temperature dependence of its resistivity. Indeed, at low temperature, resistivity behaves like a highly anisotropic 3D Fermi-liquid, but low metallic transport has been reported for the in-plane resistivity at high temperature while the out-of-plane resistivity possesses a transition from metallic to incoherent transport mechanism around 130K which remains unexplained. In order to shed light on these phenomena, we carried out ab initio calculations to compute the electron-phonon coupling in SRO in the framework of density functional theory as implemented in the Quantum ESPRESSO suite. Then, using the EPW module, we report the temperature dependent phonon-mediated resistivity of SRO as computed from the Iterative Boltzmann Transport Equation scheme. |
Tuesday, March 16, 2021 3:36PM - 3:48PM Live |
J20.00004: Assessing the sensitivity of electron momentum densities and Fermi surfaces to different exchange-correlation approximations. Eddie Harris-Lee, Alyn David Neil James, Stephen B Dugdale Density-functional theory has been remarkably successful at predicting the Fermi surfaces of a wide variety of metallic systems, these being tested by a range of experimental techniques. Yet, in some cases these predictions can be more successful than in others. For example, whereas the experimentally measured Fermi surface of Mo is accurately predicted by LDA calculations, notable differences have been observed for Cr [1]. By performing various calculations (including SCAN [2] and QSGW [3]) we have investigated the extent to which this discrepancy, as well as those in other materials, can be attributed to the exchange-correlation approximation. Observed improvements to Fermi surface predictions will be discussed. |
Tuesday, March 16, 2021 3:48PM - 4:00PM Live |
J20.00005: Recent developments in PyProcar: A Python library for electronic structure pre/post-processing Uthpala Herath, Pedram Tavadze, He Xu, Eric Bousquet, Sobhit Singh, Reese Boucher, Logan Lang, Freddy Farah, Francisco Muñoz, Aldo H Romero We present our recent updates to PyProcar, a robust, open-source Python package providing graphical representations for electronic structure calculations. PyProcar is capable of performing a multitude of tasks including plotting plain and spin/atom/orbital projected band structures and Fermi surfaces (in 2D and 3D), unfolding bands of a super cell into predefined unit cell, comparing band structures from multiple DFT calculations, plotting PDOS and generating a k-path for a given crystal structure. Additionally, PyProcar plots Fermi surfaces which map colors depending on other properties (e.g. electron velocity, electron-phonon mean path, effective mass) when provided a file with a desired specific property evaluated for each k-point in a k-mesh and for each band. PyProcar can be conveniently used in a stand-alone command line mode or a library mode, accessible through the Python packaging index and conda. It currently supports VASP, Elk, Quantum Espresso, Abinit, Lobster and Siesta. |
Tuesday, March 16, 2021 4:00PM - 4:12PM Live |
J20.00006: Embedded cluster density approximation for exchange-correlation energy Chen Huang We have developed a local correlation method in the framework of Kohn-Sham density functional theory (KS-DFT). The method is termed embedded cluster density approximation (ECDA), which is a logical extension of the local density approximation. In ECDA, an embedded cluster is defined for each atom, and the cluster’s exchange-correlation (XC) energy density is calculated using advanced, orbital-based XC functionals. System's XC energy is then constructed by patching these locally computed, high-level XC energy densities in an atom-by-atom manner. An efficient approach for calculating XC potential is derived, ,making ECDA a fully self-consistent method for studying charge reorganization in heterogeneous materials. ECDA is a variational method, and analytical forces are derived. To further reduce the cost of ECDA, we showed that environments can be treated using orbital-free DFT. Numerical tests show that ECDA can be applied to various systems that have different types of bonds. ECDA is a nearly "black-box" method, and we expect it to be a simple, yet effective method to scale up high-level KS-DFT calculations in large systems. |
Tuesday, March 16, 2021 4:12PM - 4:24PM Live |
J20.00007: Asymptotic behavior of the exchange-correlation energy density and the Kohn-Sham potential in density functional theory: exact results and strategy for approximations Eli Kraisler
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Tuesday, March 16, 2021 4:24PM - 4:36PM Live |
J20.00008: The Fermi-Löwdin orbital self-interaction correction (FLO-SIC) method with periodic boundary conditions Koblar Jackson, Juan E Peralta, Kushantha Withanage, Alexander Johnson, Tunna Baruah, Dimitrios A Papaconstantopoulos, John Perdew, Mark Pederson The Fermi-Löwdin orbital self-interaction correction (FLO-SIC) method was developed recently to allow an efficient implementation of the Perdew-Zunger formalism for removing electron self-interaction from approximate density functional calculations. FLO-SIC has been shown to yield improved properties for a wide variety of atomic and molecular systems. In this talk we describe how FLO-SIC can be extended to systems with three-dimensional periodicity. We use diamond as a prototypical example to discuss how localized Fermi-Löwdin orbitals (FLOs) are obtained from the canonical Bloch functions and how the FLOs can be used, in turn, to obtain periodic solutions. We will also describe efforts to affirm the importance of SIC for describing localized to itinerant behavior in f-electron materials.[1] |
Tuesday, March 16, 2021 4:36PM - 4:48PM Live |
J20.00009: Self-Interaction Correction in F-Electron Systems Alexander Johnson, Chandra Shahi, Mark Pederson Approximations to density functional theory typically overestimate the electronic coulomb energy in quantum systems and the origin of this overestimate leads to especially large self-interaction errors in rare earth containing molecules and materials. For example, in the Ln row, DFT often underestimates the number of f-electrons in the neutral atom compared to experiment. The self-interaction correction (SIC) cures the prevalent self-interaction error in DFT calculations and is known to localize orbitals. Calculations addressing the role of the self-interaction correction for correcting the electronic valence configuration in the elements of the lanthanide series are presented using the Fermi-Löwdin Orbital Self Interaction Correction (FLOSIC) methodology.[1] The work presented here utilized a newly developed tool for algorithmic parallelization of the solution of Poisson’s equation, and for selecting FODs within the Naval Research Laboratory Molecular Orbital Library (NRLMOL). |
Tuesday, March 16, 2021 4:48PM - 5:00PM Live |
J20.00010: Laplacian-level meta-GGA for the exchange-correlation energies of metals Aaron Kaplan, John Perdew Common meta-generalized gradient approximations (meta-GGAs) for the exchange-correlation energy of many-electron systems use the non-interacting kinetic energy density (KED) to identify and describe local chemical properties. KED-level meta-GGAs are exceedingly accurate for diverse insulating systems, but often worsen GGA-level descriptions of metallic systems. This talk will motivate the development of a non-empirical Laplacian-level meta-GGA using semiclassical turning surface arguments [1] and observed trends. I will discuss how exact constraints can be built into a Laplacian-level meta-GGA and the limitations inherent to the level of approximation. The functional form, numeric efficiency, and accuracy of such a functional will also be presented, particularly for the structural, magnetic, and energetic properties of alkalis and transition metals. Comparisons to recent KED-level meta-GGAs [2] and an outlook on future meta-GGAs will be featured. |
Tuesday, March 16, 2021 5:00PM - 5:12PM Live |
J20.00011: Self-Interaction Corrected Electronic Structure of a Cu-based Molecule using Fermi-Löwdin Orbitals Anri Karanovich, Yoh Yamamoto, Koblar Alan Jackson, Kyungwha Park Density-functional theory has been successful in studying properties of molecules and solids, but the approximate exchange-correlation functionals include self-interaction errors, which highly affect electronic and magnetic properties of strongly correlated systems including transition-metal based compounds. A recently developed self-interaction corrections (SIC) method is based on the SIC potential generated by localized Fermi-Löwdin orbitals (FLO) which depend on the positions of Fermi orbital descriptors (FODs). The success of this FLO-SIC method relies on good initial FODs, which are often nontrivial, yet there are no routine approaches to generate them for transition-metal systems. In order to understand the SIC effect on 3d-element systems as a function of initial FODs, taking a Cu-based molecule as a nontrivial example, we systematically generate the initial FODs based on the molecular symmetry and compute the electronic structure in two charge states. Our results from the FLO-SIC method are compared to the results from the generalized-gradient approximation without SIC. |
Tuesday, March 16, 2021 5:12PM - 5:24PM Live |
J20.00012: Analysis of Finite-Temperature Thomas-Fermi Theory in One Dimension John Kozlowski, Natali Fisher, Aurora Pribram-Jones, Kieron Burke In recent decades, finite-temperature Density Functional Theory has proven very useful in its direct application to warm dense matter simulations. These Kohn-Sham calculations typically make use of a standard Generalized Gradient Approximation, ignoring any temperature-dependent exchange-correlation corrections. Much is still unknown about the temperature-dependence of local and semilocal approximations in DFT. Thomas-Fermi (TF) theory applied to Kohn-Sham electrons offers a natural starting point for analysis, yielding a first look at the temperature-dependent errors. We utilize model systems both to analyze and discuss the performance of finite-temperature TF theory, giving insight into the temperature-dependence of its various errors. A simple correction to the finite-temperature TF energy is proposed, using simple one-dimensional systems as illustrative examples. |
Tuesday, March 16, 2021 5:24PM - 5:36PM Live |
J20.00013: Accurate molecular geometries in complex excited-state potential energy surfaces with optimally-tuned range-separated hybrids Bernhard Kretz, David Egger The computational investigation of the excited-state (ES) potential energy surfaces (PES) involved in important photocatalytic reactions (e.g., water splitting) can shed light on reaction mechanisms and pathways. These ES PES can be obtained using time-dependent density functional theory (TD-DFT) or high-level wave-function methods. Calculations based on TD-DFT are computationally very efficient but often do not reach the accuracy of computationally more expensive wave-function methods[1]. One promising approach to reduce this gap in accuracy is the recently developed class of optimally-tuned range-separated hybrid (OT-RSH) functionals[2]. |
Tuesday, March 16, 2021 5:36PM - 5:48PM Live |
J20.00014: DFT Studies of Phosphorene Nanostructures for DNA Sequencing Matthew B. Henry, Benjamin Tayo The need for enhanced DNA sequencing techniques at the resolution of individual nucleobases is ever-increasing and research into new methods seeks to provide rapid, high-resolution, and cost-effective sequencing of longer strands. The single-layer nature of 2D materials make them ideal materials for use in rapid DNA sequencing at single-base resolution. Despite the large number of 2D materials, most research efforts have mostly focused on a small number of candidates such as graphene, MoS2, and hexagonal boron nitride. In this talk, we present the results of density functional theory (DFT) studies of the interaction of phosphorene nanomaterials with DNA bases. We observe that phosphorene nanomaterials show a characteristic change in the density of states for each base. Furthermore, the band gap of phosphorene nanoribbon is significantly changed compared to other nanomaterials (e.g., MoS2, graphene, h-BN, and silicene) due to physisorption of bases on nanoribbon surface. Our findings show that phosphorene is a promising material for DNA base detection using advanced detection principles such as transverse tunneling current measurement. |
Tuesday, March 16, 2021 5:48PM - 6:00PM Live |
J20.00015: An efficient density functional for accurate molecular chemisorption and physisorption on transition metal surfaces Manish Kothakonda, Ruiqi Zhang, Jinliang Ning, James Furness, Jianwei Sun Understanding molecular adsorption on transition metal surfaces underpins many problems in heterogeneous catalysis. Accurately predicting the adsorption energies has been a challenging task as simultaneously capturing chemical and van der Waals (vdW) interaction in a single density functional is difficult. In this work, we propose a new density functional [Opt(MS+rVV10)] by combining a semi-local meta-generalized gradient approximation (MGGA) Made Simple (MS) [1] with revised Vydrov-van Voorihs (rVV10) vdW correction[2], with two key parameters in MGGA-MS and one in rVV10 simultaneously refitted to the atomization energies of covalently bonded small molecules and the Ar2 binding curve. The resulting Opt(MS+rVV10) functional is validated for 39 molecular adsorptions on transition metal surfaces[3], showing improved and balanced descriptions for both physisorption and chemisorption in comparison with popular vdW-corrected density functionals. |
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