Bulletin of the American Physical Society
APS March Meeting 2018
Volume 63, Number 1
Monday–Friday, March 5–9, 2018; Los Angeles, California
Session A02: Developments of DFT from Quantum to Statistical Mechanics (I)Focus

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Sponsoring Units: DCP DCOMP Chair: Jianzhong Wu, University of California, Riverside Room: LACC 150B 
Monday, March 5, 2018 8:00AM  8:36AM 
A02.00001: Localized Orbital Scaling Correction for Systematic Elimination of Delocalization Error in Density Functional Approximations Invited Speaker: Weitao Yang The delocalization error of common density functional approximations leads to diversified problems in presentday density functional theory calculations. For achieving a universal elimination of delocalization error, we develop a localized orbital scaling correction (LOSC) framework, which unifies our previously proposed global and local scaling approaches. The LOSC framework accurately characterizes the distributions of global and local fractional electrons, and is thus capable of correcting system energy, energy derivative and electron density in a selfconsistent and sizeconsistent manner. The LOSC–DFAs lead to systematically improved results, including the dissociation of cationic species, the band gaps of molecules and polymer chains, the energy and density changes upon electron addition and removal, and photoemission spectra. (ref: Chen Li,1 Xiao Zheng, Neil Qiang Su, and Weitao Yang, “Localized Orbital Scaling Correction for Systematic Elimination of Delocalization Error in Density Functional Approximations”, DOI: 10.1093/nsr/nwx111) 
Monday, March 5, 2018 8:36AM  8:48AM 
A02.00002: Directly Patching ExchangeCorrelation Energy in Density Functional Theory Chen Huang KohnSham density functional theory is widely used nowadays for largescale material simulations, however its accuracy is limited by the accuracy of the exchangecorrelation (XC) functionals. We will discuss our effort on developing the exchangecorrelation energy patching (XCEP) method in which for each atom (called central atom) we select its nearby atoms as its buffer atoms. The central atom and its buffer atoms form the cluster. The rest atoms form the environment. The system’s electron density is then partitioned among the cluster and environment using the finitetemperature density functional embedding theory developed recently in our group. The obtained cluster is a small KS system, whose XC energy density can be computed using a highlevel XC functional. The system’s XC energy is constructed by patching these highlevel, local XC energy densities over the entire system in an atombyatom manner. The performance of XCEP is investigated by patching the random phase approximation correlation energy in some onedimensional systems, and by patching the exact exchange energy in molecules. We show that by increasing the clusters’ sizes the XCEP results converge to the benchmarks. 
Monday, March 5, 2018 8:48AM  9:00AM 
A02.00003: How Derivative Discontinuities in the Energy Yield Interatomic Steps in the Exact KohnSham Potential of DensityFunctional Theory Eli Kraisler, Matt Hodgson, Axel Schild, Eberhard K Gross Accurate densityfunctional calculations hinge on reliable approximations to the unknown exchangecorrelation (xc) potential. The most popular approximations usually lack features of the exact xc potential that are important for an accurate prediction of the fundamental gap and the distribution of charge in complex systems. Two principal features in this regard are the spatially uniform shift in the potential, as the number of electrons infinitesimally surpasses an integer, and the spatial steps that form, e.g., between the atoms of stretched molecules. Although both aforementioned concepts are wellknown, the exact relationship between them remained unclear. In this talk, we establish this relationship and introduce a new concept: the chargetransfer derivative discontinuity, Δ^{CT}. By numerically solving the manyelectron Schrödinger equation, we extract the exact KohnSham potential and directly observe its features, particularly the spatial interatomic steps. For the first time, spatial steps are observed in the exact xc potential of a threedimensional full configurationinteraction (FCI) calculation of a molecule. 
Monday, March 5, 2018 9:00AM  9:12AM 
A02.00004: Temperature and the stronginteraction limit of density functional theory Aurora PribramJones The strictly correlated electron approach to density functional theory, first proposed by Seidl and coworkers [14], offers a unique perspective on finitetemperature density functional theory and one of its application areas, simulations in the warm dense matter regime. Recent work relating tied coordinatetemperatureinteraction scaling to the stronginteraction limit of density functional theory is presented via formal and numerical results. Strategies for analyzing the competition between strong interaction and temperature in complicated physical systems will be discussed. 
Monday, March 5, 2018 9:12AM  9:24AM 
A02.00005: Comparison of electronic properties of atoms with d orbitals using coupledcluster singles and doubles (CCSD) and selfenergy functional theory Taichi Kosugi, Hirofumi Nishi, Yoritaka Furukawa, Yuichiro Matsushita We examine the electronic correlation effects of isolated atoms containing d orbitals by using calculations based on the CCSD and the selfenergy functional theories. The selfenergy functional theory[1] was proposed originally for analyzing models of correlated systems. We adopt it for realistic description of the atoms by employing exact diagonalization of their secondquantized Hamiltonians. We calculate the singleparticle Green's functions[2] to clarify how the manybody nature of the atoms affects on the spectral functions. We also discuss the differences in the spectra between both methods. 
Monday, March 5, 2018 9:24AM  9:36AM 
A02.00006: Comprehensive study of coupledcluster singles and doubles Green function (GFCCSD) on periodic systems Yoritaka Furukawa, Taichi Kosugi, Hirofumi Nishi, Yuichiro Matsushita Coupledcluster singles and doubles (CCSD) is known to reproduce electronic correlation with high accuracy. By employing the Green’s function developed within the CCSD scheme (GFCCSD), one is capable of obtaining physical quantities including energy spectrum [1]. No periodic system, however, has been treated by GFCCSD except for electron gas [2]. In this work, we have developed a code to calculate the oneparticle Green’s functions of periodic systems through GFCCSD and applied it to several realistic materials. We have found that the spectral functions and the band structures well exhibit the effects of the electronic correlation. We have also examined the differences between the calculated and experimental results. 
Monday, March 5, 2018 9:36AM  10:12AM 
A02.00007: Classical DFT of Ions in the Electrical Double Layer and Nanofluidics Invited Speaker: Dirk Gillespie Compared to DFTs of shortrange interactions (e.g., hard spheres), the longrange Coulombic interaction poses a special problem for developing classical density functional theory for ions and electrolytes. Over the last 25 years, significant progress has been made on more accurate DFTs for Coulombic systems. Recent progress in such DFTs will be reviewed. Applications of DFTs of electrolytes to the equilibrium electrical double layer (including 2D DFT calculations of a heterogeneous surface charge) and in the transport of ions in nanofluidic systems will be discussed. 
Monday, March 5, 2018 10:12AM  10:24AM 
A02.00008: Direct Extraction of Excitation Energies from Ensemble DensityFunctional Theory Zenghui Yang, Aurora PribramJones, Kieron Burke, Carsten Ullrich A very specific ensemble of ground and excited states is shown to yield an exact formula for any excitation energy as a simple correction to the energy difference between orbitals of the KohnSham ground state. This alternative scheme avoids either the need to calculate many unoccupied levels as in timedependent density functional theory (TDDFT) or the need for many selfconsistent ensemble calculations. The symmetryeigenstate Hartreeexchange (SEHX) approximation yields results comparable to standard TDDFT for atoms. With this formalism, SEHX yields approximate double excitations, which are missed by adiabatic TDDFT. 
Monday, March 5, 2018 10:24AM  10:36AM 
A02.00009: Orbitalfree density functional theory with atomcentered density matrices William Witt, Johannes Dieterich, Florian Libisch, Emily Carter Orbitalfree density functional theory (OFDFT) is one of the most computationally efficient methods for performing electronic structure calculations. OFDFT achieves its speed by treating the electron density as the sole quantity of interest, in contrast to KohnSham density functional theory which incorporates singleparticle wave functions. The lack of wavefunction manipulations makes OFDFT suitable for the study of millions of atoms, provided it can be made sufficiently accurate. 
Monday, March 5, 2018 10:36AM  10:48AM 
A02.00010: On the development of nonadiabatic functionals in realtime TDDFT Lionel Lacombe, Johanna Ildemar Fuks, Neepa Maitra TimeDependent Density Functional Theory (TDDFT) has made remarkable achievements in the description of excitation spectra and response properties. On the other hand, for the description of dynamical processes in the nonlinear regime, the adiabatic approximation is widely used, with groundstate DFT functionals that depend only on the instantaneous density. In systems driven far from equilibrium, memorydependence can dramatically affect the shape of the exact exchangecorrelation potential, and as a result, adiabatic approximations give poor predictions of the dynamics. 
Monday, March 5, 2018 10:48AM  11:00AM 
A02.00011: The GW SelfScreening Error and its Correction Using a Local DensityFunctional Jack Wetherell, Matthew Hodgson, Rex Godby In electronic structure theory, the selfscreening error is the part of the selfinteraction error that would remain within the GW approximation if the exact dynamically screened Coulomb interaction W were used, causing each electron to artificially screen its own presence. In the GW approach to manyelectron theory, the selfscreening introduces error into the electron density, energy and ionization potential. We illustrate this selfscreening error in a straightforward way for model systems using orbitaldependent potentials. We propose a simple, computationally inexpensive correction to any GW calculation (including fully selfconsistent GW) to remove this error. Our correction is a spatially local potential, added to the selfenergy, that depends on the local electron density, obtained via a series of onedimensional oneelectron finite training systems. We then test our correction for other onedimensional systems where we have access to the exact manyelectron density and energy, and show that our correction removes the unwanted effects of selfscreening on the electron density and the ionization potential. 
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