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Next-generation Codes for Excited States and Response Functions Real-space and Real-time

Next-generation Codes for Excited States and Response Functions Real-space and Real-time. J. J. Rehr Department of Physics, University of Washington Seattle, WA, USA. *Supported by the DOE and the DOE CMSN. Code Development Goals.

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Next-generation Codes for Excited States and Response Functions Real-space and Real-time

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  1. Next-generation Codes for Excited States and Response FunctionsReal-space and Real-time J. J. Rehr Department of Physics, University of Washington Seattle, WA, USA *Supported by the DOE and the DOE CMSN

  2. Code Development Goals • Predict excited state and response properties over the full spectrum of energies,length, & time scales: X-ray spectra, optical response, vibrations, time-dependent phenomena, transport, … • Key issues: Physics beyond independent particle approximation in real-space, real-time, finite-temperature … Excitation spectra: inelastic losses, satellite, multiplets, …

  3. Strategy • Develop user-friendly theoretical tools linking Excited stateproperties to existing ground state codes DFT + GW- BSE, RT-TDDFT, DFT/MD, … • Applications • X-ray Spectroscopies (XAS, EXAFS, XES, RIXS, XMCD, …) • Optical response • Relativistic Electron Energy Loss Spectra (EELS) • Real-time linear and non-linear response No single code has these capabilities!

  4. Linked-codes • FEFF9+ ABINIT , GAUSSIAN , VASP , ORCA → Real-space Green’s function code – full spectrum response → X-ray Spectra: XAS, EELS, NRIXS, XMCD, →Optical constants, scattering factors ... → Real-time: DFT/MD, ab initio Debye-Waller factors • AI2NBSE / OCEAN (NBSE + ABINIT + MPSE) → User-friendly GW/BSE code for optical / core response • TD-SIESTA ( Crank-Nicolson + SIESTA ) Real-time TDDFT → linear & non-linear response

  5. FEFF9 Parameter free RSGF theory JJR et al., ComptesRendus Physique 10, 548 (2009) in Theoretical Spectroscopy L. Reining (Ed) (2009)

  6. JFEFF – JAVA GUI

  7. Ex post facto self-energy corrections OCEAN + MPSE PARATEC + MPSE

  8. X-ray-Optical Absorption Spectra (XAS) fcc Al arXiv:cond-mat/0601242 http://leonardo.phys.washington.edu/feff/opcons UV X-ray Photon energy (eV)

  9. Real-time approaches for linear and nonlinearoptical & xray response J. J. Rehr, Y.Takimoto, and F. Vila Department of Physics University of Washington Seattle, WA USA Excitations in Condensed Matter: From Basic Concepts to Real Materials Time (s) FEFF + DFT/MD RT - SIESTA KITP, UCSB November 17, 2009

  10. That’s all folks!

  11. NRIXS and EELS S(q,ω) FEFF8-NRIXS J.A.Soininen, A.L. Ankudinov, JJR Phys. Rev. B 72, 045136 (2005) Finite q No selection rules – need all multipoles!

  12. Expt BSE* feff(q) * back

  13. Electron energy loss spectra (EELS) fcc Al -Im ε-1 UV X-ray Photon energy (eV)

  14. FEFF + ABINITF. Vila (UW) Phonons + IR

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