Transcript 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
• 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, …
Strategy
• Develop user-friendly theoretical tools linking
Excited state properties 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!
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
FEFF9
Parameter free
RSGF theory
JJR et al., Comptes Rendus
Physique 10, 548 (2009)
in Theoretical Spectroscopy
L. Reining (Ed) (2009)
JFEFF – JAVA GUI
Ex post facto self-energy corrections
OCEAN + MPSE
PARATEC + MPSE
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)
Excitations in Condensed Matter: From Basic Concepts to
Real Materials
Real-time approaches for linear and
nonlinear optical & xray response
J. J. Rehr, Y.Takimoto, and F. Vila
Department of Physics
University of Washington
Seattle, WA USA
Time (s)
FEFF + DFT/MD
RT - SIESTA
KITP, UCSB November 17, 2009
That’s all folks!
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!
Expt
BSE*
feff(q)
*
back
Electron energy loss spectra (EELS)
-Im ε-1
fcc Al
UV
X-ray
Photon energy (eV)
FEFF + ABINIT F. Vila (UW)
Phonons + IR
 
2

i


0
  coth
D jl , j 'l '
2

2
2
2






Q


 D  Qi
i
d
1
2E

m j m j ' 1 2 u jl u j 'l '
 6  step Lanczos recursion 
Dynamical Matrix


from ABINIT/Gau ssian03