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First Principles Molecular Dynamics

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First Principles Molecular Dynamics First-Principles Molecular Dynamics F. Gygi 1, M. LaCount1, M. Govoni2, M. He2,3, H. Zheng3, V. Rozsa2, A. Gaiduk2, G. Galli2,3 1University of California Davis,2Institute for Molecular Engineering, University of Chicago, 3Argonne National Laboratory Client-Server Operation DFT MD Reference Datasets • Qbox can be used by other codes as a "DFT-engine" • The availability of reference datasets allows for quantitative • Generates DFT/hybrid-DFT energies and forces comparisons of density functionals • Generates density response to arbitrary external potentials • C++/MPI/OpenMP implementation of FPMD • Focus on H2O, relevant to several applications • Communication implemented through the file system • Large-scale parallelism (used on up to 128k cores on ANL Mira) • PBE400 Dataset • Qbox-SSAGES coupling • 32-sample ensemble simulations, PBE, T=400 K • New developments • Free energy calculations using PBE and PBE0 energies and forces • W. Dawson, F. Gygi, J. Chem. Phys. 148, 124501 (2018) • Implementation of the SCAN meta-GGA functional • SCAN330 Dataset • Implementation of RSH (range-separated hybrid), DDH (dielectric dependend hybrid), HSE (Heyd- Scuseria-Ernzerhof) hybrid functionals • Perdew's SCAN meta-GGA functional (Sun et al. PRL 2015) • Shown to improve agreement with experiment w.r.t. PBE • Integration of recent developments • 8 independent samples, 45 ps each, T=330 K • Response to arbitrary external fields • M. LaCount, F. Gygi (in preparation) • Polarizability • Full data available online (including trajectories) • http://www.quantum-simulation.org/reference E. Sevgen, F. Giberti, H. Sidky, J.K. Whitmer, G. Galli, F. Gygi, J.J. de Pablo, JCTC 14, 2881 (2018). PBE400 SCAN330 First-Principles MD Applications 3 3 Soper 2000 Soper 2000 • Qbox-WEST coupling Soper 2013 Soper 2013 Skinner 2013 Skinner 2013 Polaron formation in non- • Calculation of the dielectric response used in GW and BSE 2.5 2.5 approximations 2 2 stoichiometric WO3 gOO(r) gOO(r) • Multiple Qbox instances running in parallel 1.5 (r) 1.5 OO g gOO(r) 1 1 δV(r) 0.5 0.5 δn(r) 0 0 2 2.5 3 3.5 4 4.5 5 2 2.5 3 3.5 4 4.5 5 r (Angstrom) r (Å) 0.02 0.02 δV(r) Soper 2008 Soper 2008 Stability of CdSe nanoparticles in δn(r) gOOO(θ) gOOO(θ) 0.015 0.015 contact with organic ligands ) ) -1 -1 ) (deg ) (deg θ θ 0.01 0.01 ) sin( ) sin( θ θ ( ( OOO OOO M. Gerosa, F. Gygi, M. Govoni, G. Galli, Nature Materials (2018) (in press) P P 0.005 0.005 0 0 40 60 80 100 120 140 160 180 40 60 80 100 120 140 160 180 Infrastructure θ (deg) θ (deg) Structure of the Al O /H O interface Pair correlation functions (gOO(r)) and angular 2 3 2 correlation functions (g (θ)) of ensemble simulations Software distribution OOO enable quantitative comparisons of density functionals • Qbox web site http://www.qboxcode.org • Qbox GitLab server http://scherzo.ucdavis.edu/qbox/qbox-public • GitHub mirror https://github.com/qboxcode Spectroscopy Applications • Online Documentation using Sphinx-doc Future Directions • Raman spectroscopy from FPMD simulations including calculations of polarizability • Tutorials/Examples development • Platform-independent performance • IR Spectroscopy from FPMD simulations using on-the-fly calculations of the polarization • Analysis tools • Autotuning kernels Infrared spectrum of water computed using a • Streamlining spectroscopy applications Raman spectrum of water at high pressure delectric-dependent hybrid functional (DDH) Pseudopotentials • Beyond IR or Raman simulations • Coupling through wave function sharing A B C D • SG15 collection based on Hamann ONCV formulation • M. Schlipf, F. Gygi, Comput. Phys. Comm. 196, 36 (2015) • Dynamic loading of custom plug-ins • Ongoing validation of all elements (from H to Bi) • Let users define their own Qbox command • Facilitate development/extension by new users • Curation of the SG15 pseudopotential collection at http://quantum-simulation.org • Potentials distributed in Qbox and UPF (QE) formats A. Gaiduk, J. Gustafson, F. Gygi, and G. Galli, J. Phys. Chem. Lett., 9 • Validation of the use of PBE pseudopotentials with hybrid-DFTs Supported by the U.S. Department of Energy (DOE) and the Midwest V. Rozsa, D. Pan, F. Giberti, G. Galli, PNAS, 201800123 (2018) 3068 (2018) Integrated Center for Computational Materials. We acknowledge computational resources from RCC at the University of Chicago, NERSC and ANL-ALCF. .
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