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Dpto. Física de Materiales, Universidad del País Vasco, Donostia International Physics Center (DIPC,) Donostia, Spain
http://dipc.ehu.es/arubio Email: [email protected]
Angel RubioFreie Universitat Berlin
Response functions from a TDDFTbased formalism: applications to low dimensional structures
MPIKSColloqium: International Workshop on ``Atomic Physics'', Nov. 28 Dec. 2, 2005, Dresden
Motivation: spectra, reactivity, bio, nano Basic formalism Applications to biochromophores and nanostructures (nanotubes, polymers)
Molecular transport
Physical Processes: Spectroscopies
Timedependent approach: TDDFT?
e
e
e
excited states
Ground state
transporthv
Photoexcitation and relaxation
Dark Structures in Molecular Radiationless Transitions Determined by Ultrafast Diffraction, Science, Vol 307, 558563 (2005)
R. J. Levis et al, Science 292, 709 (2001)
Quantum control Theory
Biological molecules: photoreceptors QM/MM + TDDFT approach
M.A.L Marques, X. Lopez, D. Varsano, A. Castro, and A. R. Phys. Rev. Lett. 90, 158101 (2003)
F. Gai et al. Science 279, 1886 (1998)
Bridging spatial and time scales: multiscale modeling!!!!!
J.Phys.Chem.B 108, 9646, (2004)
Electron transfer processes in molecular devices
Density Functional versus Manybody perturbation theory
groundstate
KSequationsWhat about excitedstate properties: electronion dynamics, spectroscopies
Time Dependent Density Functional Theory (Runge and Gross 1984)Electrondynamics first, then eion problem
HKlike theorem: v(r,t) <> (r,t)The time dependent density determines uniquely the timedependent external potential and therefore all physical observables
KohnSham formalism:The time dependent density of the interacting system can be calculated as the density of an auxilary noninteracting system
Same timedependent
density n(r,t)
Object 2 ?
Object 3
By the RungeGross theorem ALL observables are functionals of the TD density
Absorption spectra: from the power spectrum of the TD dipole moment d(t) = < r n(r,t) > d(w)=FT[d(t)]
........... and current response
Ionisation yields:
Excited state densities and transition probabilities
....................... and many more observables!!!!!!
Object 17
Time dependent multicomponent KS theoremtransformation to a bodyfixed coordinate frame required
T.Kreibig and E.K.U Gross PRL (2001)The densities , N of the interacting system can be calculated as
densities of a noninteracting (KS) system
potential
t (R)| g>
|e>
|(t)>=C1(t)|e>+C2(t)|g> ????
beyond BO H = E
F = m
Electron dynamics
MD
within BO
MD under electronic excitation needs to include finite lifetime
Object 8
Ehrenfest's dynamics
The octopus project is aim to the first principle description of the excite state electronion dynamics of nanostructures and extended systems within TDDFT
M.A.L. Marques, A. Castro, G. Bertsch, AR Comp.Phys.Comm. (2002)C. Rozzi, M.A.L. Marques, A. Castro, E.K.U. Gross A. R. (to be published)
http://www.tddft.org/programs/octopus
✗DFT) in the Local Density Approximation(LDA) or beyond (EXX+RPA)✗Plane wave and/or realspace grid expansion✗Pseudopotentials ✗TDDFT for Response Calculations
and excitedstate dynamicstogether with a MBPT (GW+BS) input for new fxc that deals with excitonic effects
Firstprinciple calculations
M.A.L. Marques, A. Castro, G. Bertsch, AR Comp.Phys.Comm. (2002)C. Rozzi, M.A.L. Marques, A. Castro, E.K.U. Gross A. R. (to be published)
OCTOPUS project: http://www.tddft.org/programs/octopus
Applications to biochromophores
Time Scales
Multiscale approaches are needed: time and space
QM/MM Hamiltonian For Local Phenomena
1. Warshel , A.; Levitt, M. J. Mol. Biol., 1976, 103, 2272. Field, M.J.; Bash, P.A.; Karplus, M. J. Comp. Chem., 1990, 11, 700
Why QM?
Photoexcitations Polarization??F. Gai et al. Science 279, 1886 (1998)
Van der Waals Interactions
QM/MM Electrostatics
SCF
QM/MM Boundary
HLink Atom
Reuter et al, ; J. Phys. Chem. A 2000, 104, 1720.
Green Fluorescent Protein (GFP).(Aequorea victoria: jellyfish)
A "poor" condensed matter physics view !!QM/MM + TDDFT approach
M.A.L Marques, X. Lopez, D. Varsano, A. Castro, and A. R. Phys. Rev. Lett. 90, 158101 (2003)
Green Fluorescent Protein (GFP).(Aequorea victoria: jellyfish)
Biological molecules: photoreceptors
T.M.H. Creemers et al, Proc. Natl. Acad. Sci.. USA (1999)
HSA
Neutral
HSD
HSE
HSP
AnionCation
Towards the color of plants: porphyrines
Towards the color of plants: The real Chlorophyll molecule
GOAL: address the complexity of the Photosyntetic Unit
LHIRC LHIIRC
Hu X., Damjanovic A., Ritz T., Schulten K. PNAS, 1998, 95, 5935
Azobenzene: spectroscopy along femtosecondlaser induced photoisomerization
S. Spörlein et al, Proc. Natl. Acad. Sci., 99, 7998 (2002)
HOMO
LUMO
T. Hugel et al, Science, 296, 1103 (2002) Y. Yu et al, Nature 425, 145 82003)
Azobenzene dyes are known to isomerize at the central NN bond within fractions of picoseconds at high quantum yield [T. Nägele et al, Chem. Phys. Lett. 272, 489 (1997)].
SingleMolecule Optomechanical Cycle
CIS
TRANS
Azobenzene: spectroscopy along femtosecondlaser induced photoisomerization
Nanotechnology Application: Optics of C and BN nanotubes
Bandstructure (DFTLDA)
Graphinelayer BNsheet
(transparent)(black)
NB
Simple model for the electronic structure: TB of Ctubes
Optical Absorption Spectroscopy
●structural characterisation ●Role of packing: tube-tube interaction
x
A.G. Marinopoulus, L. Reining, A.R. PRL (2003)
Optical Properties of CTubes: A way to elucidate tubechirality
Polarisation dependenceBandstructure effectsExcitonic effects (Louie and Mele)Bundling
Weismann Science (2002)Zeolite type AlPo45
N. Wang et al, Nature 408, 51 (2000)
CandidatesC(3,3)C(5,0)C(4,2)
Z.M..Lie et al, PRL (2001)
Zeolite type AlPo45
very strong“depolarization
effects”antenna
Hot carrier relaxation in nanotube
Relaxation of hole and electron after photo-excitation
Y. Miyamoto, D. Tomanek, AR (unpublished)
Ichida, et al., Physica B 323, 237 (2002)
* Time evolution of wave function with ionic motion: electron phonon coupling*Time evolution of charge density: electron-electron coupling within DFT
TDDFT-MD is parameter free and treats
Present case: (3,3) nanotube
Γ X
Randomized ionic velocities under the MaxwellBoltzmann distribution with
300K as an initial condition
23
29
Transition considered: Optically allowed, with E/(tube axis)
electron-phonon is dominant
Energy transfer with longer time-scale/9
6 at
om Potential and kinetic energy (ions)
electron-electron is dominant
Optical absorption of extended systems
G. Onida, L. Reining and AR, Rev. Mod. Phys. 74, 601 (2002)
TDDFT: Problems with standard exchangecorrelation functionals
A new fxc derived from Manybody perturbation theoryproper description of excitonic effects!!!
Object 18
Singlepole approximati
on
Independent Electrons (KS!) Hedin's GW (1965)
=KohnSham states=Plasmons/Electronhole states
The selfenergy physics
P = i G0G
0 Γ
Σ = iG0W
W=v+vP0W
Γ=δ+δΣ/δG G0G
0Γ
G = G0 + G
0 (Σ v
xc) G
Dyson's Eqn
+ Abs α
Screening effects: ε = 1 – v P polarisation
ManyBody approach to the ExchangeCorrelation Kernel of TDDFT
A. Marini, R. Del Sole and AR, PRL (2003) L. Reining, V. Olevano, AR, G. Onida, PRL88, 0664041 (2002);F. Sottile et al, PRL (2004) ; S. Botti et al, PRB (2004).; F. Bruneval et al (2005)
HypothesisIt exists a ''manybody xckernel'' such that the TDDFT and ManyBody polarization
functions are identical
Consequently TDDFT equation can be used as an equation for the xckernel and as a formal solution can be found in terms of an iterative equation for
the nth order contribution
ManyBody approach to the ExchangeCorrelation Kernel of TDDFT
A. Marini, R. Del Sole and AR, PRL (2003) L. Reining, V. Olevano, AR, G. Onida, PRL88, 0664041 (2002);F. Sottile et al, PRL (2004) ; S. Botti et al, PRB (2004).; F. Bruneval et al (2005)
4point equations!!!!
BN nanotubes Dimensionality effect: Exciton in (quasi) 1D, 2D, 3D
L. Wirtz, A. Marini, AR (2005)
Park, Spataru, Louie (2005)Wirt, Marini, Rubio (2005)
Exciton localisation in C and BN nanotubes
Frenkel
High Luminiscence yield in BN!!!
Low dimensional systems (1D): polyacetylane
M. van Faassen et al. PRL 88 186401 (2002) S.J.A. Van Gisbergen PRL 83 694 (1999)
Electric field dependence of the XC Potential in Molecular Chains
In LDA and GGA xc potential lack of a term counteracting the applied electric field
Low dimensional sytems (1D): polyacetylane Isolated infinite Polyacetylene chain
D. Varsano, A. Marini, AR (2005)
Low dimensional sytems (1D): polyacetylane
Low dimensional sytems (1D): polyacetylane Finitesize chains
Longitudinal polarizabilty per Monomer
HF values taken from Champagne et al PRA 52 1039 (1995)VK values taken from M. Van Faasen PRL 88 186410 (2002)
D. Varsano, A. Marini, AR (2005)
Low dimensional sytems (1D): polyacetylane
D. Varsano, A. Marini, AR (2005)
Finitesize chains
1D
Effects not discussed in the present work that would be important
Memory effects and initial state dependence of the XC functionalDissipation ; lifetimes ; decoherence
Spatial nonlocality: XC derivative discontinuity Orbitaldependent functionalsChargetransfer excitationsNonadiabatic effects in the excite state ion dynamics. (relation to geometrical phases!)
Summary for finite systemsTDDFT is a powerful tool to handle the combined dynamics of electron/ion in
response to external electromagnetic fields of nanostructures, biological molecules and extended systems.
Problem: we need better xc functionals
Molecular Transport
QUESTIONS?
✔Ground-state DFT? J(r,t); virtual excitations
Landauer formalism: steady-state theory valid for independent electrons and if the underlying electron theory is DFT the resonant tunneling is at the wrong energies, therefore this theory would not give the exact current even in the exact XC is used.
Similar problem for present implementations of Non equilibrium Greens functions approach based on DFT
✔Dissipation effects: Temperature and e-phon coupling?
✔Role of contacts and the molecule: weak versus strong coupling
Object 4
Why time dependent Transport?✔ allows the study of transients, AC effects, laser fields, etc..
✔ allows a proper description of non-equilibrium processes since excitation energies are accessible in TDDFT in contrast to DFT
✔ allows the inclusion of interaction effects, i.e., the longitudinal current of TDDFT is equal to the exact longitudinal current of the interacting system if the exact XC is used (an alternative would be TD-current DFT)
perturbation local in space
S. Kurt, G. Stefanucci, C.O. Amblath, AR , E.K.U Gross, PRB72, 35308 (2005)
Electron pumping
net current in the device by applying a TD potential to the device regionRealisation: pumping in C nanotubes using surface acustic waves (Archimidean screw, ca. 250 bc)
ConclusionsTheoretical spectroscopy is nowadays a very reliable tool to
characterising nanostructures, biomolecules and their assemblies
MBPT marriage with TDDFT
The optics of lowdimensional structures is dominated by excitons luminiscence can be drastically increased by exciton localisation Weak diameter dependence in BN nanotubes “The ultranonlocal” potential needed for describing the optical properties of polyacetylane is captured by the new developed TDDFT xckernel
Molecular Transport: description of the nonequilibrium dynamics
Acknowledgements
M. A. L. Marques, F. Sottile, X. López, L Wirtz, D. Varsano Department of Material Physics, Centro Mixto CSICUPV, University of the Basque
Country, and Donostia International Physics Center (DIPC), Donostia, Spain
L. Reining, V. OlevanoÉcole Polytechnique, Palaiseau, France
A. Marini and R. Del Sole Istituto Nazionale per la Fisica della Materia e Dipartimento di Fisica
dell'Università di Roma ``Tor Vergata'', Roma, Italy
A. Castro, C.A. Rozzi, S. Kurth, G. Stefanucci, and E. K. U. GrossInstitut für Theoretische Physik, Freie Universität, Berlin, Germany
Femtosecond dynamics: High Harmonic Generation
Harmonic Spectrum of H2
Object 6
Object 7
ω=1.6eVI
peak=1014W/cm2
Harmonic Spectrum of C6H
6
1, (nN±1)(n=1,2,...)
Identification of Identification of SW defects by SW defects by optically induced optically induced local vibrationlocal vibration
Optical excitation on Stone-Wales defects in nanotubes
hybridized state(hole)
* state (electron)
6 eV
Y. Miyamoto, S. Beber, M. Yoon, D. Tomanek, AR , PRB (2004)
Å
=17 fs (1962cm-1)
Å
Excitation with ultraviolet
Excitation with infrared
Twodimensional spectroscopy of electronic couplings in photosynthesis Nature 434, 625 (2005)