ab initio calculations on local excited states of lanthanide and actinide ions in solids luis seijo...

Ab initio calculations on Ab initio calculations on local excited states oflocal excited states of

lanthanide and actinide ions in solidslanthanide and actinide ions in solids

Luis Seijo and Zoila BarandiaránLuis Seijo and Zoila Barandiarán

Departamento de Química &Departamento de Química &Instituto Universitario Instituto Universitario dede Ciencia de Materiales Nicolás Cabrera Ciencia de Materiales Nicolás Cabrera

Universidad Autónoma de Madrid, Spain.Universidad Autónoma de Madrid, Spain.

http://www.uam.es/quimica/aimp

Dedicated to Professor Russell PitzerDedicated to Professor Russell Pitzer








First-principles theoretical methods…First-principles theoretical methods…

are are they useful as a collaborative tool in the they useful as a collaborative tool in the field of 4f-5d, 5f-6d, … kind of excitations?field of 4f-5d, 5f-6d, … kind of excitations?

Dedicated to Professor Russell PitzerDedicated to Professor Russell Pitzer

Int. Symp. on Molecular Spectroscopy - Russ Pitzer Symposium, Columbus, Ohio, June 16-20 2008 4

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Ions of Lanthanides and Actinides in solidsIons of Lanthanides and Actinides in solids

• LanthanidesLanthanides– Many technological applicationsMany technological applications

Phosphors for Solid-State Lighting devices (SSL); Phosphors for Solid-State Lighting devices (SSL); lasers; scintillators; quantum cutters; … lasers; scintillators; quantum cutters; …

– Supported on basic researchSupported on basic research• Experiments, theory (semiempirical models)Experiments, theory (semiempirical models)

– First-principles calculations should be able to help (if doable and First-principles calculations should be able to help (if doable and reliable)reliable)

• speeding up the development of new materials with targeted speeding up the development of new materials with targeted properties, via computational modeling properties, via computational modeling (e.g. (e.g. new phosphors for SSL devices, …)new phosphors for SSL devices, …)

• supporting and/or providing interpretations of experiments supporting and/or providing interpretations of experiments (e.g. spectroscopic assignments, decay mechanisms, …)(e.g. spectroscopic assignments, decay mechanisms, …)

• providing some data which are hard to get from experiments alone providing some data which are hard to get from experiments alone (e.g. nature and structure of defects in ground and excited states, …)(e.g. nature and structure of defects in ground and excited states, …)


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• ActinidesActinides– Basically, one but very relevant applicationBasically, one but very relevant application

Advanced Nuclear Energy Systems (ANES), radioactive waste Advanced Nuclear Energy Systems (ANES), radioactive waste management management

– Basic research is needed, but experiments are very restricted by Basic research is needed, but experiments are very restricted by technical conditionstechnical conditions

– First-principles calculations face the same technical conditions First-principles calculations face the same technical conditions than in lanthanidesthan in lanthanides

– They should be able to help in actinides even more than in They should be able to help in actinides even more than in lanthanideslanthanides


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• Methodological demandsMethodological demands– Bonding interactionsBonding interactions– Correlation (non-dynamic and dynamic; multireference)Correlation (non-dynamic and dynamic; multireference) – Relativistic effects (scalar and spin-orbit coupling)Relativistic effects (scalar and spin-orbit coupling)– Host embedding effectsHost embedding effects– Large manifolds of excited statesLarge manifolds of excited states


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MethodsMethods

• Ab initio; embedded-cluster; wave functionAb initio; embedded-cluster; wave function– AIMP embedding:AIMP embedding:

• Coulomb + exchange + linear independence (Pauli)Coulomb + exchange + linear independence (Pauli)

– CGWB-AIMP Hamiltonian (2-component relativistic)CGWB-AIMP Hamiltonian (2-component relativistic)– step 1) SA-CASSCF + MS-CASPT2step 1) SA-CASSCF + MS-CASPT2– step 2) sfss-MR-SOCI step 2) sfss-MR-SOCI


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ProgramsPrograms

– MOLCASMOLCAS (B. O. Roos et al., Lund University, Sweden) (B. O. Roos et al., Lund University, Sweden)

– COLUMBUSCOLUMBUS (R. M. Pitzer et al., Ohio State Univ., USA) (R. M. Pitzer et al., Ohio State Univ., USA)– EPCISOEPCISO (V. Vallet et al., Univ. de Lille, France) (V. Vallet et al., Univ. de Lille, France)


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Embedded-cluster calculationsEmbedded-cluster calculations

• All relevant interactions are includedAll relevant interactions are included– Within the clusterWithin the cluster

• Bonding, relativity (scalar, spin-orbit), dynamic correlationBonding, relativity (scalar, spin-orbit), dynamic correlation

– Between the cluster and the rest of the crystalBetween the cluster and the rest of the crystal• Coulomb, exchange, linear-independence (Pauli)Coulomb, exchange, linear-independence (Pauli)

• Structures can be optimized in the excited statesStructures can be optimized in the excited states– Luminescence can be modeledLuminescence can be modeled (not only absorption)(not only absorption)


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Some representative resultsSome representative results

UU3+3+ in Cs in Cs22NaYClNaYCl66


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UU3+3+-doped Cs-doped Cs22NaYClNaYCl66

Absorption spectrum 14000-50000 cmAbsorption spectrum 14000-50000 cm-1-1

M. Karbowiak et al., JCP 108 (1998) 10181; JPC 108 (2004) 6397


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• 1998 (experiment)1998 (experiment)– Region IRegion I

• Very complex 5f6d bands of U3+.• Five electronic origins found, but not assigned.

– Region IV not commented.Region IV not commented.– Regions II + III not reported.Regions II + III not reported.

• 2003 (theory)2003 (theory)– Region IRegion I

• Basic interpretation supported: 5f6d(t2g) absorptions of U3+.• The five electronic origins are assigned.• Many other electronic origins in the region. Multiorigin bands.

– Region IVRegion IV• Forbidden double excitations on U3+: 5f6d + 5f5f

– 5f26d(eg)1 manifold starts at 42000 cm-1, at the spin-orbit free level of calculation. (Related to future region IIIregion III)

JCP 118 (2003) 5335


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M. Karbowiak et al., JCP 108 (1998) 10181

FFive electronic origins of very complex 5five electronic origins of very complex 5f33 5f 5f226d6d1 1

bands bands ffoundound, , but but not assignednot assigned..


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Spin-free MS-CASPT2 calculations Spin-free MS-CASPT2 calculations 2S+1=4 only2S+1=4 only


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L. Seijo, Z. Barandiarán JCP 118 (2003) 5335

44KK11/211/2

44II9/29/2

44GG5/25/2

44HH7/27/2

11 7g7g15 04015 04011 6g6g15 16015 16022 8g8g15 17015 170

33 8g8g16 12016 12044 8g8g16 50016 500

22 7g7g17 13017 130

66 8g8g18 01018 01033 6g6g18 42018 420

11 8g8g14 70014 700 14 14 157157

22 6g6g16 04016 040 15 15 682682

55 8g8g16 99016 990 16 16 528528

33 7g7g17 98017 980 1717 600600

77 8g8g19 72019 72044 6g6g19 72019 72055 7g7g20 21020 210

44 7g7g19 44019 440 19 19 200200

88 8g8g20 39020 39099 8g8g20 42020 420

55 6g6g20 48020 4801010 8g8g20 85020 85066 6g6g21 18021 18066 7g7g21 19021 190

……

Calc. Exp. Calc. Exp.

------

----

----

--

----------

--------


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• Very complex 5f6d bands of U3+.• Five electronic origins found, but not assigned.

– Region IV not commented.Region IV not commented.– Regions II + III not reported.Regions II + III not reported.


• Basic interpretation supported: 5f6d(t2g) absorptions of U3+.• The five electronic origins are assigned.• Many other electronic origins in the region. Multiorigin bands.

– Region IVRegion IV• Forbidden double excitations on U3+: 5f6d + 5f5f

– 5f26d(eg)1 manifold starts at 42000 cm-1, at the spin-orbit free level of calculation. (Related to future region IIIregion III)

JCP 118 (2003) 5335


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• 2003 (theory; U2003 (theory; U4+4+-doped Cs-doped Cs22ZrClZrCl66))– 5f6d(t2g) absorptions start at 31000


• Two additional origins found.• The seven electronics origins assigned on the basis of the ab

initio results. The existence of more origins is recognized.• (2005) Three more origins identified and assigned with CFT

– Region IV: ab initio interpretation adopted.Region IV: ab initio interpretation adopted.– Region II reported.Region II reported.

• 5f6d(t2g) absorptions of U4+ (spontaneous oxidation)(spontaneous oxidation), on the basis of ab initio results on U4+-doped Cs2ZrCl6.

– Region III reported.Region III reported.• 5f6d(eg) absorptions of U3+, on the basis of spin-free ab initio

results.

JCP 118 (2003) 7439

M.Karbowiak, CP 314 (2005) 189


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• Detailed interpretationDetailed interpretation• 24 electronic origins assigned24 electronic origins assigned

JCP 127 (2007) 144712


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Experimental absorption spectrum 14000-21000 cmExperimental absorption spectrum 14000-21000 cm-1-1

M. Karbowiak et al., JCP 108 (1998) 10181; JPC A 108 (2004) 6397; CP 314 (2005) 189


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Ab initio calculationAb initio calculation

F. Ruipérez et al., JCP 127 (207) 144712

I-A I-B I-C I-D


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F. Ruipérez et al., JCP 127 (2007) 144712


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Some representative resultsSome representative results

CeCe3+3+ in YAG in YAG


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CeCe33++ in YAG in YAG

• Phosphor used in commercial white solid-state-lighting Phosphor used in commercial white solid-state-lighting devicesdevices– GaN blue LED + YAG:CeGaN blue LED + YAG:Ce3+3+ blue-to-yellow downconverter blue-to-yellow downconverter

Phosphor

White Light

CeCe3+3+-doped-doped YAG YAG

• Can the blue absorption be simulated?

• And the yellow emission?


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CeCe33++ substitutes for Y substitutes for Y33++ in a D in a D22 site of Y site of Y33AlAl55OO1212


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DD22 field field SOSO SOSODD22 field field

4f4f11 22FF

5d5d11 22DD

22BB1122BB22

22BB2222BB33

22BB1122BB33

22AA

22BB11

22BB33

22AA

22AA

22BB22

55

55

55

55

55

55

4f4f11 22FF

5d5d11 22DD

22FF7/27/2

22DD3/23/2

22FF5/25/2

22DD5/25/2


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21740 cm-1

44840 cm-1

29410 cm-1

26880 cm-1

CeCe3+3+ in YAG: Absorption spectrum in YAG: Absorption spectrum

21740 cm-1

26880 cm-1

Wavelength (nm)

55(2(222A)A)22330 cm-1

448 nm55(3(322BB33))

31460 cm-1

318 nm

55(3(322A)A)47140 cm-1

210 nm

55(1(122BB22))

Inte

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YAG:(CeOYAG:(CeO88AlAl22OO44))15-15-

G. J. Zhao et al., Phys. Stat. Sol. (a), 199 (2003) 355

J. Gracia et al., J. Lumin., 128 (2008) 1248


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18870 530

17860 560

CeCe3+3+ in YAG: Luminescence in YAG: Luminescence

55(2(222A)A)

Wavelength (nm)

Inte

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arb

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55(1(122BB22))

460 nm

506 nm

55(1(122A)A)

55(1(122BB33))

55(2(222BB11))

55(1(122BB11))

55(2(222BB22))55(2(222BB33))

21730 cm-1

19760 cm-1

G. J. Zhao et al., Phys. Stat. Sol. (a), 199 (2003) 355

YAG:(CeOYAG:(CeO88AlAl22OO44))15-15-J. Gracia et al., J. Lumin., 128 (2008) 1248


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Y. Zorenko et al., J. Lumin., 114 (2005) 85


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• Absorption spectrum is okAbsorption spectrum is ok ( (energies and intensity profileenergies and intensity profile))• LuminescenceLuminescence

– Intensity profile is okIntensity profile is ok– Energies are overestimatedEnergies are overestimated

• Stokes shift is too small Stokes shift is too small – 600 cm600 cm-1-1 instead of 2870 cm instead of 2870 cm-1-1

– Insufficient excited state distortionInsufficient excited state distortion• Limitations of the theoretical model?Limitations of the theoretical model?

• Excited state symmetry lower than DExcited state symmetry lower than D22??

– Pseudo Jahn-Teller in 10Pseudo Jahn-Teller in 10ΓΓ55(3(322A), A), the third 5dthe third 5d11 state; NOT in the state; NOT in the luminescent stateluminescent state..

• Are Are antisite defects (AD)antisite defects (AD) involved in the luminescence? involved in the luminescence?

J. L. Pascual

A. B. Muñoz


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YAG unit cellYAG unit cell

160 atoms/unit cell

Y 24(c) D2

Al6 16(a) S6

Al4 24(d) S4

O 96(h)

Ia3d (Oh10)


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Y-AlY-AlOhOh antisite defects of YAG antisite defects of YAG

SIESTA: DFT(GGA) PBCSIESTA: DFT(GGA) PBC

A. B. Muñoz


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A. B. Muñoz


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ConclusionsConclusions

• State-of-the-art wave function based State-of-the-art wave function based ab initioab initio calculations calculations of of 4f-5d4f-5d and and 5f-6d5f-6d absorptions and emissions of f-element absorptions and emissions of f-element ions doped in solids are feasible and reliable.ions doped in solids are feasible and reliable.

• Feasibility is enhanced by high symmetry and limited by Feasibility is enhanced by high symmetry and limited by the sizes of the local defects and the sizes of the the sizes of the local defects and the sizes of the manifolds.manifolds.

• Reliability demands: relativity (scalar & spin-orbit); static Reliability demands: relativity (scalar & spin-orbit); static correlation ([4f5d6s]correlation ([4f5d6s]NN multireference); dynamic multireference); dynamic correlation (ligands + Ln(correlation (ligands + Ln(5s5p4f5d6s5s5p4f5d6s)); techniques for )); techniques for large manifolds; and a good embedding.large manifolds; and a good embedding.

• In use as a collaborative tool; ready to be exploited.In use as a collaborative tool; ready to be exploited.


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AcknowledgmentsAcknowledgments

Fernando Ruipérez

Fernando Ruipérez

José Gracia

José Gracia

Zoila Barandiarán

Zoila Barandiarán

José Luis Pascu

al

José Luis Pascu

al

Ana Belén Muñoz

Ana Belén Muñoz

Belén Ordejón

Belén Ordejón


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Goar Sánch

ez

Goar Sánch

ezNoémi B

arros

Noémi Barro

s


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• Russell Pitzer (OSU, Columbus, Ohio)Russell Pitzer (OSU, Columbus, Ohio)• spin-orbit codespin-orbit code

• Norman Edelstein (LBNL, Berkeley, California)Norman Edelstein (LBNL, Berkeley, California)• PaPa4+4+, Ce, Ce3+3+, Sm, Sm2+2+, …, …

• Miroslaw Karbowiak (University of Wroclaw, Poland)Miroslaw Karbowiak (University of Wroclaw, Poland)• UU4+4+

• Wouter van Gennip (Philips Lighting, Eindhoven, The Netherlands), Wouter van Gennip (Philips Lighting, Eindhoven, The Netherlands), Hans Niemantsverdriet (Eindhoven University of Technology, The Hans Niemantsverdriet (Eindhoven University of Technology, The Netherlands)Netherlands)

• YAG:CeYAG:Ce3+3+

• Ministry of Education and Science, Spain, CTQ2005-08550Ministry of Education and Science, Spain, CTQ2005-08550• Universidad Autónoma de MadridUniversidad Autónoma de Madrid• Philips Lighting, Eindhoven Philips Lighting, Eindhoven

This is paper of Zoila Barandiarán and Luis SeijoThis is paper of Zoila Barandiarán and Luis Seijo in honor of Russ Pitzer in honor of Russ Pitzer

and his contributions in electronic structure theoryand his contributions in electronic structure theory

ab initio calculations on local excited states of lanthanide and actinide ions in solids luis seijo...

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