calculation of x-ray absorption spectra
DESCRIPTION
Calculation of x-ray absorption spectra. Christian Brouder Institut de Minéralogie et de Physique des Milieux Condensés. Theoretical approaches. A bit of history One body Two bodies Many bodies. The malediction of XAFS calculations. Kronig (1931) Petersen (1932) Bogdanovich (1937) - PowerPoint PPT PresentationTRANSCRIPT
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Calculation of x-ray absorption spectraCalculation of x-ray absorption spectra
Christian BrouderChristian BrouderInstitut de Minéralogie et de Physique des Milieux CondensésInstitut de Minéralogie et de Physique des Milieux Condensés
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A bit of historyA bit of historyOne bodyOne bodyTwo bodiesTwo bodiesMany bodiesMany bodies
Theoretical approachesTheoretical approaches
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Kronig (1931)Kronig (1931)Petersen (1932)Petersen (1932)Bogdanovich (1937)Bogdanovich (1937)Natoli (1980)Natoli (1980)
The malediction of The malediction of XAFS calculationsXAFS calculations
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One-body calculationOne-body calculation
The main approachesThe main approaches
Two-body calculationsTwo-body calculations
Many-body calculationsMany-body calculations
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One-bodyOne-body
nn||nn||.r.r||00>|>|22 ((nn--
00-E)-E)
V(V(rr)) )) nn((rr) = ) = nn nn((rr) )
V = VV = Vcc+V+Vxcxc DFT LDA Kohn-ShamDFT LDA Kohn-Sham
V = VV = Vcc++ Green function theoryGreen function theory
00((rr) core-hole wavefunction ) core-hole wavefunction
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The book of Buddha garlands (~400)The book of Buddha garlands (~400)Lord Rayleigh (1892)Lord Rayleigh (1892)Kasterin (1897)Kasterin (1897)Korringa (1945,1947)Korringa (1945,1947)Kohn Rostoker (1953)Kohn Rostoker (1953)
Multiple-scattering theoryMultiple-scattering theory
Indra’s netIndra’s netAvatamsaka sutraAvatamsaka sutra
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The muffin-tin approximationThe muffin-tin approximation
Spherical atoms in a constant interstitial potential
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The muffin-tin approximationThe muffin-tin approximation
Spherical atoms in a constant interstitial potential
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CONTINUUM (Natoli, 1980)CONTINUUM (Natoli, 1980)ICXANES (Durham et al., 1982)ICXANES (Durham et al., 1982) http://cpc.cs.qub.ac.uk/summaries/AARR.html
FEFF8 (Rehr et al., 1991)FEFF8 (Rehr et al., 1991) http://leonardo.phys.washington.edu/feff/
SPRKKR (Ebert et al., 1998)SPRKKR (Ebert et al., 1998) relativistic olymp.cup.uni-muenchen.de/ak/ebert/SPRKKR/
MXAN (Benfatto et al., 2002)MXAN (Benfatto et al., 2002) [email protected]
PY-LMTO (Antonov et al., 2001)PY-LMTO (Antonov et al., 2001) relativistic LMTO [email protected]
Muffin-tin programsMuffin-tin programs
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Non muffin-tinNon muffin-tin
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Non-muffin-tin programsNon-muffin-tin programs
FPX (Foulis, 1986-2002)FPX (Foulis, 1986-2002) Non-muffin-tin multiple scattering
www.esrf.fr/computing/scientific/fpx/fpx.htm
WIEN2k (Blaha et al., 1998)WIEN2k (Blaha et al., 1998) FP-LAPW
www.wien2k.at/
FDMNES (Joly, 2001)FDMNES (Joly, 2001) Finite difference method 147.173.148.95/LDC/LE_LABORATOIRE/Equipes_de_recherche/EQUIPE_SPECTROSCOPIE/SIMUL/EtudFond_Prog.asp
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Non-muffin-tin programsNon-muffin-tin programs
PARATEC (Cabaret et al., 2002)PARATEC (Cabaret et al., 2002) pseudopotential
www-ext.lmcp.jussieu.fr/~cabaret/xanes.html
EXC!TING (Dewhurst et al., 2006)EXC!TING (Dewhurst et al., 2006) FP-LAPW
exciting.sourceforge.net/
STOBE (Saint-Amant et al., 1992)STOBE (Saint-Amant et al., 1992) LCAO
www.fhi-berlin.mpg.de/th/th.html
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Bethe-SalpeterBethe-SalpeterL=LL=L00+L+L00KLKL
LL00(12;1’2’)=G(1,2’)G(2,1’)(12;1’2’)=G(1,2’)G(2,1’)
The dielectric response The dielectric response (x,y) (x,y) <0|[j(x),j(y)]|0> <0|[j(x),j(y)]|0>can be obtained from Lcan be obtained from L
Two-bodyTwo-body
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BS + TDDFT programsBS + TDDFT programsADF (Stener et al., 2003)ADF (Stener et al., 2003) TDDFT
www.scm.com/
DP (Olevano et al., 1999)DP (Olevano et al., 1999) TDDFT pseudopotential
theory.polytechnique.fr/codes/dp/dp.html
EXCEXC Bethe-Salpeter pseudopotential
theory.polytechnique.fr/codes/exc/exc.html
NBSE (Shirley, 1998)NBSE (Shirley, 1998) Bethe-Salpeter pseudopotential
physics.nist.gov/Divisions/Div844/staff/Gp4/shirley.html
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Many-body statesMany-body states
Many-bodyMany-body
nn||nn||.r|.r|00>|>|22 ((nn--00-E)-E)
iiVVnn((rrii) ) ijijVVee((rrijij)) |)) |nn> = > = nn | |nn> >
||00> > many-bodymany-body ground stateground state
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Multiplet programsMultiplet programs
TT-MULTIPLETS (Thole et al., 1990)TT-MULTIPLETS (Thole et al., 1990) www.anorg.chem.uu.nl/people/staff/FrankdeGroot/ttmultiplets.htm/
Cluster (Kotani et al., 1992)Cluster (Kotani et al., 1992) theo.phys.okayama-u.ac.jp/~okada/index_e.html/
AMARCORD (Mirone, 2000)AMARCORD (Mirone, 2000) www.esrf.fr/computing/scientific/people/mirone/amarcord/
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ProblemsProblems
Green functions and KS-(TD)DFTGreen functions and KS-(TD)DFT One-particle orbitals are occupied or not
Restricted to closed shell systems
MultipletsMultiplets parametrized very small systems
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Unifying approachesUnifying approaches
Multichannel multiple scatteringMultichannel multiple scattering Krüger and Natoli (2004)
TDDFT for open shellsTDDFT for open shells in progress (E.K.U Gross and coll.)
Green functions with correlationGreen functions with correlation in progress
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Long-term programLong-term program
CORRELATION