Bulletin of the American Physical Society
APS March Meeting 2020
Volume 65, Number 1
Monday–Friday, March 2–6, 2020; Denver, Colorado
Session D40: Building the Bridge to Exascale: Applications and Opportunities for Materials, Chemistry, and Biology IIIFocus

Hide Abstracts 
Sponsoring Units: DCOMP DMP DAMOP DCP Chair: Jack Deslippe, Lawrence Berkeley National Laboratory Room: 705 
Monday, March 2, 2020 2:30PM  3:06PM 
D40.00001: Preparing for exascale: additive manufacturing process modeling at the fidelity of the microstructure Invited Speaker: James Belak In FY17, the USDOE Exascale Computing Project (ECP) initiated projects to design and develop simulation codes to use exascale computing. This application development is organized around computational motifs. Here, we present an overview of the motifs of computational materials science, from the “particles” using by molecular dynamics to the “grids” using by phasefield models and the various solution algorithms such as FFTs. Examples will be taken from the codesign centers ExMatEx and CoPA, as well as the application development project ExaAM. This project includes an integration of all the computational components of the metal additive manufacturing (AM) process into a coupled exascale modeling environment, where each simulation component itself is an exascale simulation. What has emerged is that exascale computing will enable AM process modeling at the fidelity of the microstructure. Here we discuss what this means, in particular, tight coupling of ProcessStructureProperty calculations. Macroscopic continuum codes (ALE3D, Truchas and OpenFOAM) are used to simulate meltrefreeze, within which mesoscopic codes (Phasefield and Cellular Automata) are used to simulate the development of material microstructure. This microstructure is then used by polycrystal plasticity codes (ExaConstit) to calculate local material properties. The project is driven by a series of demonstration problems that are amenable to experimental observation and validation. We present our coupled exascale simulation environment for additive manufacturing and its initial application to AM builds. 
Monday, March 2, 2020 3:06PM  3:18PM 
D40.00002: Enabling First Principles MultiscaleMultiphysics Simulations of Complex ThermoFluid Systems Through Exascale Computing Joseph Oefelein, Kyle Schau, Ramanan Sankaran Understanding and controlling turbulence, aerothermodynamics, and propulsion processes in advanced thermofluid systems presents many challenges. A multitude of strongly coupled fluid dynamic, thermodynamic, transport, chemical, and heat transfer processes are intrinsically coupled and must be considered simultaneously in complex domains. These multiscale physics are not currently understood or modeled with sufficient accuracy. Without their inclusion, timely Research and Development of advanced systems will be significantly deficient. Exascale computing offers significant opportunities treat these physics with unprecedented accuracy and speed. However, the foundational hybridCPU+GPU architectures present many challenges to exploit their full potential power. This presentation will highlight the inherent challenges associated with porting complex multiphysics solvers to these architectures and the approach taken to achieve optimal performance using the RAPTOR code framework developed by Oefelein et al. as an example application. 
Monday, March 2, 2020 3:18PM  3:30PM 
D40.00003: Generating a Comprehensive Map of Cancer Morphology in Whole Slide Tissue Specimens Joel Saltz, Raj Gupta, Dimitris Samaras, Le Hou, Han Le, Shahira Abousamra, Rebecca Batiste, Tianhao Zhao, Jingwei Zhang, Chao Chen, Tahsin Kurc Advanced imaging technologies can capture extremely highresolution images of tissue specimens, and quantitative analyses of cancer morphology using these images have shown value in a variety of correlative and prognostic studies. Our work on Summit will generate a comprehensive multiscale mapping of cancer morphology with a dataset of more than 10,000 whole slide tissue images from over 20 cancer types. The work will use a collection of deep learning analysis pipelines we have developed to study, quantify and characterize tissue structure in diseased and normal tissue specimens. These analysis pipelines generate distributions of nuclei and cells and patchlevel maps of lymphocyte distributions and segmentations of tumor regions. The analysis results will provide a firstever representations of lymphocyte maps, nuclear characterizations and characterizations of tumor regions on a dataset of this scale. We expect that studies supported by these rich datasets will enable the development of biomarkers to predict clinical outcome and a better epidemiological understanding of cancer subtypes and how constituent cells contribute to cancer invasion and expansion. 
Monday, March 2, 2020 3:30PM  3:42PM 
D40.00004: Operator Dynamics in Quantum Circuits with Subsystem Symmetry Jason Iaconis, Sagar Vijay, Rahul Nandkishore Our understanding of quantum dynamics in manybody quantum systems has been revolutionized in recent years by the study of random quantum circuits. These models provide a tractable setting in which we can understand ideas such as thermalization, operator spreading and quantum chaos. Furthermore, it is known that a richer variety of phenomena can occur when such models are enriched with a set of symmetries. We will focus on a particularly exotic set of symmetries which act on lower dimensional submanifolds of our system, a situation which is relevant to the study of highly quantum 'fracton' phases of matter. I will discuss approaches we may take to simulate such quantum dynamics numerically in higher dimensional systems. In particular, we will see that a restricted class of automaton circuit dynamics can be efficiently simulated while retaining the essential attributes of generic quantum chaotic systems. This technique will allow us to understand the properties of circuits with subsystem symmetry and may provide a valuable new tool for future studies of chaotic quantum dynamics. 
Monday, March 2, 2020 3:42PM  3:54PM 
D40.00005: Radiationmatter interaction in graphene molecules: implementation on Geant 4 and computational simulations Carlos Vidal, John Prias, Hernando Ariza The voxelized computational approximation of the graphene molecules for different amounts of carbon atoms was simulated, using computational programs with optimized Geant 4 type geometry. The computational simulation of radiation transport throught matter with characteristic interactions in the UvVis spectral range, were made for radiation sources, detectors and graphene molecules. The optimization of the theoretical UvVis spectra obtained from Geant 4, was achieved through algorithms development on Matlab. A method for computational reconstruction of UVVis spectra was proposed. The results suggest that is possible observe the contributions of the conjugated pi and sigma bonds, in the UVVis characteristic spectra as expected. Also, it was found that the variation in the size of the graphene molecules, influence the height of the band associated with the sigma bond, in agreement with experiments broadly studied. As well as, the proposed methodology suggests Geant 4 as a potential tool to simulate radiationmatter interactions in graphenebased molecules. 
Monday, March 2, 2020 3:54PM  4:06PM 
D40.00006: ExaTN  A Scalable Exascale Math Library for Hierarchical Tensor Network Representations and Simulations in Quantum ManyBody Theory and Beyond Dmitry Liakh, Eugen Dumitrescu, Gonzalo Alvarez, Tiffany Mintz, Alexander McCaskey Tensor network theory has recently paved the path to efficient numerical simulations of two and threedimensional manybody Hamiltonians describing strongly correlated quantum particles, but it still requires efficient software infrastructure that scales well on leadership heterogeneous HPC systems. To address this need, we develop ExaTN: A scalable math library for processing hierarchical tensor representations. Our library enables the use of advanced hierarchical tensor network states capable of expressing local expectation values in strongly entangled quantum systems efficiently. ExaTN allows building arbitrarily complex tensor networks for which it exposes a set of highlevel API functions which automate tensor optimization procedures. A highly modular design of ExaTN allows seamless switching of computational backends for the computer system of choice, from a laptop to a leadership GPUaccelerated HPC platform, like Summit. The internal taskbased parallel runtime then assures a loadbalanced execution of tensor processing workloads. 
Monday, March 2, 2020 4:06PM  4:18PM 
D40.00007: Porting ITensor to Julia Matthew Fishman, Katharine Hyatt, Miles Stoudenmire In this talk, we present ITensors.jl, a groundup rewrite of the C++ ITensor library in Julia. ITensor is a leading software package for simulating quantum manybody systems with tensor networks. Julia is a relatively young justintime (JIT) compiled language that is particularly well suited for scientific computing. We will discuss the advantages and disadvantages of moving from C++ to Julia, including ease of development and performance. We will also discuss new designs for the Julia version that are in development or planned, such as a rewrite of the sparse tensor library optimized with multithreading, new tensor contraction backends, automatic fermion sign support, GPU support, and automatic differentiation for the automated optimization of tensor networks. 
Monday, March 2, 2020 4:18PM  4:30PM 
D40.00008: Breaking the entanglement barrier: Tensor network simulation of quantum transport Michael Zwolak, Marek M Rams The recognition that large classes of quantum manybody systems have limited  or efficiently representable  entanglement in the ground and lowlying excited states led to dramatic advances in their numerical simulation via socalled tensor networks. However, global dynamics elevates many particles into excited states, and can lead to macroscopic entanglement (seen both experimentally and theoretically) and the failure of tensor networks. Here, we show that for quantum transport  one of the most important cases of this failure  the fundamental issue is the canonical basis in which the scenario is cast: When particles flow through an interface, they scatter, generating a "bit" of entanglement between spatial regions with each event. The frequency basis naturally captures that  in the long time limit and in the absence of an inelastic event  particles tend to flow from a state with one frequency to a state of identical frequency. Recognizing this natural structure yields a striking  exponential in some cases  increase in simulation efficiency, greatly extending the attainable spatial and time scales. The concepts here broaden the scope of tensor network simulation into hitherto inaccessible classes of nonequilibrium manybody problems [see arXiv:1904.12793]. 
Monday, March 2, 2020 4:30PM  4:42PM 
D40.00009: Accelerate Science on Perlmutter with NERSC Charlene Yang, Jack Richard Deslippe Towards exascale computing, the National Energy Research Scientific Computing (NERSC) Center has procured a ~100 PetaFLOP/s supercomputer called Perlmutter. This talk will give an overview of its architectural details and discuss what Perlmutter can offer to the scientific community especially to Material Science and Chemistry. These offerings not only include cuttingedge hardware and technology but also highly optimized software stack and expert user support. The NERSC Exascale Science Application Program (NESAP) provides resources such as hackathons with performance engineers, early access to hardware, and NERSCfunded PostDocs to select application teams, and lessons learned from these teams are then disseminated to the general community. NERSC also collaborates with vendors and other High Performance Computing (HPC) developers on math libraries, performance models and tools, compiler development and performance portability. With an emphasis on Material Science and Chemistry, we will pinpoint the opportunities that Perlmutter and NERSC can bring for exascale and beyond. 
Monday, March 2, 2020 4:42PM  4:54PM 
D40.00010: Central Moment Lattice Boltzmann Method with FokkerPlanck Guided Collision for NonEquilibrium Flows William Taylor Schupbach, Kannan Premnath, Farzaneh Hajabdollahi Central momentsbased lattice Boltzmann method (LBM), a recent approach for flow simulations, is generally based on the relaxation of various central moments to their equilibria under collision. The latter is usually constructed either directly from the Maxwell distribution function or by exploiting its factorization property. We propose a central moment LBM from a different perspective, where its collision operator is constructed by matching the changes in different discrete central moments under collision to the changes in the corresponding continuous central moments as given by the FokkerPlanck (FP) collision model of the Boltzmann equation. The resulting formulation can be interpreted in terms of the relaxation of the various central moments to “equilibria” that depend only on the adjacent, lower order postcollision moments. We designate such newly constructed chain of equilibria as the Markovian central moment attractors and the relaxation rates are based on scaling the drift coefficient of the FP model by the order of the participating moment. We will demonstrate the accuracy and robustness of our new formulation for simulations of a variety of flows using the standard D2Q9 and D3Q27 lattices and also present a comparison against other collision models. 
Monday, March 2, 2020 4:54PM  5:06PM 
D40.00011: Nonlocal Coulomb interaction and spin freezing crossover: A route to valenceskipping charge order Siheon Ryee, P. Sémon, Myung Joon Han, Sangkook Choi Multiorbital systems away from global halffilling host intriguing physical properties promoted by Hund's coupling. Despite increasing awareness of this regime dubbed Hund's metal, effect of nonlocal interaction is still elusive. Here we study a threeorbital model with 1/3 filling (two electrons per site) including the intersite Coulomb interaction V. Using the GW plus extended dynamical meanfield theory, the valenceskipping charge order transition is shown to be driven by V. Most interestingly, the instability to this transition is significantly enhanced in the spinfreezing crossover regime, thereby lowering the critical V to the formation of charge order. This behavior is found to be closely related to the population profile of the atomic multiplet states in the spinfreezing regime. In this regime, maximum spin states are dominant in each total charge subspace with substantial amount of one and threeelectron occupations, which leads to almost equal population of one and the maximum spin threeelectron state. Our finding unveils another feature of the Hund's metal, and has potential implications to the broad range of multiorbital systems as well as the recently discovered charge order in ironpnictides. 
Monday, March 2, 2020 5:06PM  5:18PM 
D40.00012: Improved methods for demonstrating that AKLT systems are gapped Nicholas Pomata, TzuChieh Wei We examine recent advancements in proving the gaps of AKLT systems [1,2], in particular those proposed by AbdulRahman et al. [1], which we have later extended so that it can be applied numerically in more general settings. We discuss how this has been used in proving the AKLT gap on a variety of "decorated" lattices in 2D, where the number n of decorating spin1 sites on each edge of the original lattice is two or larger [3]. Furthermore, we investigate whether the gappedness can be established for several decorated lattices with n=1. We will further explore how the method may be used to demonstrate the existence of the AKLT gap on several uniform lattices without decoration. 
Follow Us 
Engage
Become an APS Member 
My APS
Renew Membership 
Information for 
About APSThe American Physical Society (APS) is a nonprofit 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 207403844
(301) 2093200
Editorial Office
100 Motor Pkwy, Suite 110, Hauppauge, NY 11788
(631) 5914000
Office of Public Affairs
529 14th St NW, Suite 1050, Washington, D.C. 200452001
(202) 6628700