Bulletin of the American Physical Society
APS March Meeting 2020
Volume 65, Number 1
Monday–Friday, March 2–6, 2020; Denver, Colorado
Session D58: DFT and Beyond IIIFocus

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Sponsoring Units: DCP DCOMP DPOLY DCMP Chair: Michele Pavanello, Rutgers University, Newark Room: Mile High Ballroom 3B 
Monday, March 2, 2020 2:30PM  3:06PM 
D58.00001: The Connector Theory Approach: Principles and Development of New Density Functionals Invited Speaker: Lucia Reining

Monday, March 2, 2020 3:06PM  3:18PM 
D58.00002: Nonadiabatic electron dynamics in timedependent densityfunctional theory at the cost of adiabatic local density approximation. Dmitry Gulevich, Yaroslav V. Zhumagulov, Alexei V. Vagov, Ilya V. Tokatly, Vasili Perebeinos We propose a computationally efficient approach to nonadiabatic electron dynamics in timedependent density functional theory (TDDFT) based on a representation of the frequencydependent exchange correlation kernel as a response of a set of damped oscillators. The requirements to computational resources needed to implement our approach do not differ from those of the standard realtime TDDFT in the adiabatic local density approximation (ALDA). Our result offers an exciting opportunity to take into account temporal nonlocality and memory effects in calculations with TDDFT in quantum chemistry and solid state physics for unprecedentedly low costs. We present few simple approximations to nonadiabatic exchangecorrelation kernels and their application to study nonadiabatic dynamics of electron liquid in semiconductor quantum wells and atoms. 
Monday, March 2, 2020 3:18PM  3:30PM 
D58.00003: Imitating beyondDFT calculations via external onsite potentials Nitin Kumar, Stephan Lany Density functional theory (DFT) based methods are the basis for the highthroughput calculations of structural and electronic properties currently used in most MaterialsbyDesign approaches for materials discovery. To improve the accuracy of such predictive theory, it is now necessary to bridge the gap between efficient, but approximate, DFT calculations, and accurate, but computationally expensive, “beyondDFT” approaches, such as GW electronic structure and random phase approximation (RPA) total energy calculations. In this direction, we aim to reproduce the beyondDFT level by using angularmomentum and energydependent external onsite potentials. The problem of fitting the potential parameters is equivalent to solving a multiobjective optimization problem. Using VO2 as a model system, we develop a workflow for potential fitting via machine learning, so to explore the extensive multidimensional search space for the highly nonlinear objective function. 
Monday, March 2, 2020 3:30PM  3:42PM 
D58.00004: First Principles Derivation of the Effect of Geometric Noise on Distributions of Electronic Properties using the Effective Stochastic KohnSham Potential Method Jeremy Scher, Arindam Chakraborty Obtaining ensemble averages by sampling many conformations is vital for an accurate description of temperaturedependent properties of chemical systems. However, constructing distributions of 10^{5}  10^{6} samples is computationally challenging due to the high computational cost of performing calculations. In this work, we present a new approach called the effective stochastic KohnSham potential (ESKS) method to address this challenge. Using the classical nuclearnuclear repulsion energy as a metric, we derive statistical relationships between the distribution of nuclearnuclear repulsion energies and the distributions of ground state quantum mechanical properties for a general chemical system. The results from this analysis show that the geometric noise experienced by molecules due to solvent interaction and thermal motion can be effectively captured by an effective stochastic operator. This allows for introducing a stochastic variable in the KohnSham potential. Comparison of the analytical results with numerical DFT calculations on small molecules, semiconductor clusters, and large organic molecules with be presented. Both analytical and numerical results demonstrate the advantage of using an effective stochastic operator for performing large scale sampling of conformations. 
Monday, March 2, 2020 3:42PM  3:54PM 
D58.00005: Towards Spectroscopic Accuracy for InSilico Materials Design Ada Sedova, Anup Pandey, Anibal J. RamirezCuesta We present a new approach for enabling highly accurate prediction of nonequilibrium behavior of large supramolecular organic systems for insilico design of novel functional materials. Using datasets of INS measurements of organic molecular crystals from the highthroughput, high resolution neutron vibrational spectrometer at SNS (VISION), we obtain essential information for achieving spectroscopic accuracy in density functional theoretical descriptions of the forces acting on large organic supramolecular assemblies with strong noncovalent bonds, using high performance computing and massively parallel DFT calculations. The work will pave the way for an ability to design and test new materials using highconfidence insilico methods. 
Monday, March 2, 2020 3:54PM  4:06PM 
D58.00006: Understanding the interplay between hole localization and reactivity in photoionized water clusters using realtime TimeDependent Density Functional Theory Vidushi Sharma, Marivi Fernandez Serra Photocatalytic watersplitting on semiconductor surfaces is of topical interest for renewable energy applications, and yet, the molecular intermediates and their mutual interactions underlying photocatalysis remain poorly understood. In this work, we examine the scope of rtTDDFTbased methods for analyzing ultrafast processes in photoexcited systems. We study the response of a prototypical molecular system consisting of chains of Hbonded (H_{2}O)_{n} molecules (n=25) under photoionization. The time evolution of the photogenerated hole is captured by rtTDDFT Ehrenfest dynamics. We use a generalized gradient approximation (GGAPBE) for nonadiabatic electronion dynamics, justified by comparing dynamic hole densities computed at PBE with those at higher PBE0 level of the theory. We also compare results from rtTDDFT dynamics with those from adiabatic BornOppenheimer molecular dynamics at the GGA level, elucidating the importance of incorporating explicit nonadiabatic effects in excitedstate phenomena. The Hbond cooperativity effects in (H_{2}O)_{n}^{+} chains are identified, emphasizing their role in facilitating hole localization. Finally, we also uncover new connections between the test system and the Hbond network formed at watersemiconductor interfaces. 
Monday, March 2, 2020 4:06PM  4:18PM 
D58.00007: Approaches for NonAdiabatic Functional Approximations in TDDFT Lionel Lacombe, Neepa Maitra Several examples of electron dynamics in the nonperturbative regime highlight the need to go beyond the adiabatic approximation to achieve even a qualitatively reasonable description. This includes chargetransfer dynamics out of the groundstate, resonantlydriven dynamics, and cases of pumpprobe spectroscopy. We discuss different approaches to develop functionals that build in memory into new nonadiabatic exchangecorrelation functionals. In one, we develop densitymatrix coupled exchangecorrelation approximations, starting from an exact expression for the timedependent exchangecorrelation functional. In another, a timedependent extension of the adiabatic connection formula is developed to take advantage of couplingconstant integration. 
Monday, March 2, 2020 4:18PM  4:30PM 
D58.00008: Plasmon dispersion and the role of the exact constraints on exchangecorrelation kernels within timedependent density functional theory Adrienn Ruzsinszky, Bimal Neupane, Shiqi Ruan, Santosh Adhikari, Santosh Neupane, Niraj K. Nepal Smallwavevector excitations in Coulombinteracting systems can be decomposed into the highenergy collective longitudinal plasmon and the lowenergy singleelectron excitations. The random phase approximation (RPA) is exact in the highdensity limit but can capture the plasmonic dispersion reasonably even for densities with r_{s} > 1. The work by Tatarczyk et al. [1] found that the impact of the exchangecorrelation kernels is significant and modifies the plasmon dispersion curve. There is however a large difference in the construction and performance of the kernels investigated earlier. Our current work for the jellium model introduces recent model exchangeonly and exchangecorrelation kernels and discusses the relevance of some exact constraints [2,3] in the construction of the kernel. This work could give a further hint toward a better plasmon dispersion in realistic metals where anomalous behavior was observed with RPA. 
Monday, March 2, 2020 4:30PM  4:42PM 
D58.00009: Nonlocal energy optimized (NEO) kernel for the formation energies of alloys and surface energies of metals Bimal Neupane, Niraj Nepal, Santosh Adhikari, Adrienn Ruzsinszky

Monday, March 2, 2020 4:42PM  4:54PM 
D58.00010: Predicting the accurate structural and energetic properties of coppergold alloys using random phase approximation Niraj Nepal, Santosh Adhikari, Jefferson E Bates, Adrienn Ruzsinszky The groundstate equilibrium properties of coppergold alloys have been explored with the stateoftheart random phase approximation (RPA) [1]. The PBE, PBE revised for solids, and revised TaoPerdewStaroverovScuseria functionals by Perdew et al. predict toolow formation energies, while the SCAN slightly overestimates it. The inclusion of thermal correction or the longrange dispersion provides a negligible contribution to the formation energies estimated with semilocal density functional theory. The spinorbit coupling improves the formation energies of PBE only by 78 meV, while it intensifies the overestimation of SCAN. We found that the nonlocality present in RPA is able to describe the transition between two delocalized electron densities (bulk elemental constituents to crystallized alloys), as required to provide accurate formation energies without any further corrections. 
Monday, March 2, 2020 4:54PM  5:06PM 
D58.00011: NonAdiabatic Quantum Molecular Dynamics Investigation of Hot Carrier Dynamics in Dielectric Polymers under High Electric Fields. Thomas Linker, Subodh Tiwari, Hiroyuki Kumazoe, Shogo Fukushima, Rajiv Kalia, Aiichiro Nakano, Ramamurthy Ramprasad, Fuyuki Shimojo, Priya Vashishta NonAdiabatic Quantum Molecular Dynamics (NAQMD) is a powerful tool typically used to model excited state electronphonon dynamics under optical excitation. In this work we have ported NAQMD to study excited hot charge carriers involved in dielectric break down of organic polymers under high electric fields. Organic polymers offer many advantages over inorganic dielectrics, but they are severely limited by break down under the application of high electric fields. There also remains no mechanistic method for quantitative prediction of the breakdown field in polymers, unlike inorganic materials. Here we performed a systematic study of different electric fields on hot carrier dynamics and resulting chemical damage in a slab of archetypal polymer, polyethylene. We found a critical transition occurring near the experimentally reported intrinsic breakdown field marked by strong localization of electronic states at the slab surface and emergence of hot carrier CH vibrational resonance. Such a localization transition may provide a criticallymissing prediction method for computationally screening dielectric polymers with high breakdown fields. 
Monday, March 2, 2020 5:06PM  5:18PM 
D58.00012: Nonadiabatic Electron Nuclear Dynamics in TDDFT with Variational Quantum Nuclei Kevin Lively, Guillermo Albareda, Aaron Kelly, Shunsuke Sato, Angel Rubio Electronnuclear coupling in nonequilibrium dynamics plays a fundamental role in condensed matter physics, defining behavior from phase transitions to chemical reactions. Recently the dynamics of these processes have been able to be experimentally resolved in the timedomain, requiring a theoretical framework beyond the BornOppenheimer approximation to describe [1]. While approaches such as the multiconfiguration timedependent Hartree method have been successful at describing excited state dynamics of relatively small systems, the cost to precompute potential energy surfaces and nonadiabatic couplings becomes a significant bottleneck for larger systems. In this talk we develop a trajectory based variational ansatz which treats the electronic system at the level of timedependent density functional theory, while simultaneously incorporating a nonadiabatic quantum mechanical description of the nuclei. This method is compared to multitrajectory Ehrenfest dynamics in the resolution of nuclear effects within the optical spectrum of small molecules. 
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