Theoretical approaches to the ab-initio study of complex systems

Transcription

1 Theoretical approaches to the ab-initio study of complex systems Olivia Pulci European Theoretical Spectroscopy Facilty (ETSF), and CNR-INFM, Dipartimento di Fisica Università di Roma Tor Vergata NAST-ISM Olivia Pulci, Maurizia Palummo, Conor Hogan, Andrea Marini, Margherita Marsili, Viviana Garbuio, Adriano Mosca Conte, Elena Cannuccia, Rodolfo Del Sole

2 G ro up a c tivities Biological systems Theory Ab-initio: (NOT one puts nothing in, one gets nothing out!!) Code development 0-D Generality, transferability 0D-3D detailed physical informations 1-D Nanowires Nanoclusters 3-D 2-D Surfaces bulks Olivia Pulci, Maurizia Palummo, Conor Hogan, Andrea Marini, Margherita Marsili, Viviana Garbuio, Adriano Mosca Conte, Elena Cannuccia, Rodolfo Del Sole

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4 BEAMLINES: Optics (O. Pulci) EELS (F. Sottile) X-ray (J. Rehr) Transport (P. Bokes) Time-resolved excitations (M. Marques) Photoemission (C. Verdozzi) Raman (G. Rignanese) new

5 Developmen t of theory training Undergraduates PhD Students Post Docs Other colleagues exp + Industry! Developmen t of codes Distribution: ABINIT FHI OCTOPUS Yambo DP+EXC TOSCA Research Carrying on Projects for users

6 METHODS c MBPT c EXC hν v DFT 1) c ωcv hν v GW 2) TDDFT W ωcv v BSE 3) Excitonic effects

7 Theory development: MB kernel for TDDFT (M. Marsili, A. Marini, R. Del Sole) PRB2003, PRL2003, PRB2007 Electron-phonon coupling (A. Marini) A. Marini Phys. Rev. Lett. 101, (2008) Vertex corrections (M. Marsili, R. Del Sole) M. Marsili, R. Del Sole, in preparation

8 G ro up a c tivities Biological systems Theory Ab-initio: (NOT one puts nothing in, one gets nothing out!!) Code development 0-D Generality, transferability 0D-3D detailed physical informations 1-D Nanowires Nanoclusters 2-D Surfaces 3-D bulks Olivia Pulci, Maurizia Palummo, Conor Hogan, Andrea Marini, Margherita Marsili, Viviana Garbuio, Adriano Mosca Conte, Elena Cannuccia, Rodolfo Del Sole

9 Daniele Varsano Andrea Marini YAMBO is a multipurpose Ab-Initio Many-Body code for excited state calculations. Conor Hogan released under the Myrta Gruning GPL license on Sept 1 st 2008 Particles(DFT) In these first 6 months... more the 5000 contacts... more the 600 downloads of the source... documentation and tutorials visited 1000 times Quasiparticles(GW) Plasmons (TDDFT) doi: /j.cpc Excitons (BetheSalpeter equation)

10 G ro up a c tivities Biological systems Theory Ab-initio: (NOT one puts nothing in, one gets nothing out!!) Code development 0-D Generality, transferability 0D-3D detailed physical informations 1-D Nanowires Nanoclusters 3-D 2-D Surfaces bulks Olivia Pulci, Maurizia Palummo, Conor Hogan, Andrea Marini, Margherita Marsili, Viviana Garbuio, Adriano Mosca Conte, Elena Cannuccia, Rodolfo Del Sole

11 0D na no do ts nanoclusters: electronic gap vs. size En = π 2 h2 n 2 2me L2 Quantum confinement M. Marsili, M. Palummo, O. Pulci

12 0D na no do ts : a bs o rption a nd em is s ion Absorption E2 C-DFT E3 Eabs Eem Excited state Ground state Emission e-h pair E4 E1 Cluster geometry Structural minimization performed both in the ground state and in presence of the e-h pair

13 0D na no do ts (O. P ulc i) h Absorption a.u. Emission Ψ exc ( re, rh ) 2 Experiment PRB 2007 PL peak related to O bridge O. Pulci in collaboration with S. Ossicini group (Modena)Ma et al. APL, (1999))

14 G ro up a c tivities Biological systems Theory Ab-initio: (NOT one puts nothing in, one gets nothing out!!) Code development 0-D Generality, transferability 0D-3D detailed physical informations 1-D Nanowires Nanoclusters 3-D 2-D Surfaces bulks Olivia Pulci, Maurizia Palummo, Conor Hogan, Andrea Marini, Margherita Marsili, Viviana Garbuio, Adriano Mosca Conte, Elena Cannuccia, Rodolfo Del Sole

15 1D na no w ires (P a lum m o ) Si Wires atomic structure d=4å

16 1D na no w ires Si NWs Excitonic Gap: theory vs exp. M.Bruno et al. PRL 2007

17 G ro up a c tivities Biological systems Theory Ab-initio: (NOT one puts nothing in, one gets nothing out!!) Code development 0-D Generality, transferability 0D-3D detailed physical informations 1-D Nanowires Nanoclusters 3-D 2-D Surfaces bulks Olivia Pulci, Maurizia Palummo, Conor Hogan, Andrea Marini, Margherita Marsili, Viviana Garbuio, Adriano Mosca Conte, Elena Cannuccia, Rodolfo Del Sole

18 2D: surfaces (ongoing projects) GaSb(001) c2x6 Conor Hogan C(111)2x1 Margherita Marsili Ice (0001) Viviana Garbuio x y

19 ISM-NAST collaboration (1): Ge(111):Sn ( 3 ) 3 R 30 : RT 3 3 : LT Eur. Phys. Lett Top view Metal semiconductor interfaces: electronic properties at the GW level and comparison experimental/calculated STM images With Paola Gori, Fabio Ronci, Stefano Colonna, and Antonio Cricenti (ISM)

20 ISM-NAST collaboration (2): 3C-SiC(001) c(4x2) Group IV surfaces: determination of actual ground state via comparison with RAS results O. Pulci, Paola Gori and Antonio Cricenti (ISM)

21 G ro up a c tivities Biological systems Theory Ab-initio: (NOT one puts nothing in, one gets nothing out!!) Code development 0-D Generality, transferability 0D-3D detailed physical informations 1-D Nanowires Nanoclusters 3-D 2-D Surfaces bulks Olivia Pulci, Maurizia Palummo, Conor Hogan, Andrea Marini, Margherita Marsili, Viviana Garbuio, Adriano Mosca Conte, Elena Cannuccia, Rodolfo Del Sole

22 ISM-NAST collaboration (3): oxides excitonic effects in ZnO Optical properties of oxides: inclusion of excitonic effects at the BSE or TDDFT level with Paola Gori and Antonio Cricenti (ISM)

23 G ro up a c tivities Biological systems Theory Ab-initio: (NOT one puts nothing in, one gets nothing out!!) Code development 0-D Generality, transferability 0D-3D detailed physical informations 1-D Nanowires Nanoclusters 3-D 2-D Surfaces bulks Olivia Pulci, Maurizia Palummo, Conor Hogan, Andrea Marini, Margherita Marsili, Viviana Garbuio, Adriano Mosca Conte, Elena Cannuccia, Rodolfo Del Sole

24 H 2O (G a rbuio -P ulc i) Absorption Electronic Gap Exp DFT BSE PRL 2006 Exciton binding energy 2.4 ev EXP-L.R. Painter et al., Phys. Rev. Lett. 21, 282 (1968) G.D. Kerr et al., Phys. Rev. A 5, 2523 (1972)

25 B io : c o nquering the enviro nm ent (M o s c a OPTICAL PROPERTIES OF INDOLE IN WATER SOLUTION BY MBPT/MM C o nte-p ulc i) A COMBINATION OF MANY BODY METHODS (GW+BSE) WITH QM/MM TO STUDY BIOLOGICAL MOLECULES IN SOLUTION QM MM A. Mosca Conte, E. Ippoliti,R. Del Sole, P. Carloni, O. Pulci, JCTC (in press)

26 Towards Biological Systems Ongoing projects: Study of solutions: formamide in water V. Garbuio Rhodopsin: retinal photoisomerization osca Conte, NAST project with L. Guidoni Flavin Cannuccia

27 Conclusions and Perspectives WHAT WE DO ab-initio electronic and optical properties of 0-3D systems WHAT WE CAN DO WITH SOME EFFORT atoms all ab-initio (hybrid methods needed) WHAT (RIGHT NOW) WE CANNOT DO (but we are working on it) excited state molecular dynamics

28 Call for projects always opened Thank you for your attention

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30 T heo ry (M a rs ili-d el S o le) GWΓ approch to band energies calculations

31 T heo ry (S a ng a lli)

32 T heo ry (S a ng a lli)

33 T heo ry (S a ng a lli)

34 T heo ry (S a ng a lli)

35 T heo ry (A tta c a lite-m a rini) Luminescence by using non-equilibrium Green Function

36 T heo ry (A tta c a lite-m a rini) Prospective: Create a theoretical and computational tool to study and predict light emission 1) Luminescence: Catho and photo luminescence 2) Role of temperature, defects and confinement 3) Non-linear Optics, optical gain, Optical Switching

37 T heo ry (A tta c a lite-m a rini) Working Plan I. Real-time dynamics of electrons by using Non-Equilibrium Green Functions. Luminescence of bulk materials i H 0 G t 1, t 2 =[U t 1 HF t 1 ]G t 1, t 2 I t 1, t 2 t1 II. Electron-phonon coupling. Relaxation through emission of phonons. Luminescence from indirect-gap systems 2 q t 1, t 2 =i g D t 1, t 2 G k q q k q t 1, t 2 III.Forces in the excited state. Luminescence from cluster, wires, polymers and defects (exciton trapping)

38 T heo ry (A tta c a lite-m a rini) Ab-initio Approach The single particle electronic states are first evaluated using density functional theory (DFT) Why Non-equilibrium G t 1, t 2 =i a t 2 a t 1 Green Functions? G t 1, t 2 = i a t 1 a t 2 Systematic approach to progressively include electronic correlation effects and electron-phonon interaction Can be used as starting point to derive approximate theory (Kinetic equations, Bloch equations, Boltzmann equations) All this theory will be implemented in ->

39 1D C O N J U G A T E D P O L Y M E R S (C a nnuc c ia -M a rini) EXCITON-VIBRON INTERACTION IN ONE DIMENSIONAL CONJUGATED POLYMERS poly(p-phenylene vinylene)... Exp. 80K Exp. 300K Bound exciton characterized by an asymmetric line-shape, together with strong vibronicinduced side bands Exp. K Pichler et al 1993 J. Phys.: Condens. Matter Theory Trans polyacetylene Phys. Rev. Lett. 82, (1999) Phys. Rev. B 38, (1988)

40 1D na no w ires (P a lum m o ) Experiment: Ma et al., Science 2003

41 1D na no w ires (P a lum m o ) Si NWs Exchange splitting : BSE theory vs Exp.

42 Y A M B O (H o g a n-m a rini) doi: /j.cpc Many-body perturbation theory: - Quasiparticle corrections (GW) - Optical and energy loss spectra including excitons and local field effects...and much more! Finite temperature. Electronphonon and polarons Real-axis GW Self-consistent COHSEX, HF, EXX... (_SC) Surface Spectroscopy Collinear and non-collinear spin Many-Body TDDFT kernel Total Energy (ACFDT)

43 1D na no w ires (P a lum m o ) Doping Si NWs: influence on the optical properties

44 1D na no w ires (P a lum m o ) GW corrections: doping and surface termination

45 2D G a S b(001) (H o g a n ) Structure and Optical Properties of Sb-stabilized G asb(001) C onor Hogan, R odolfo Del Sole (R ome) R ita M agri (M odena) c(2x10) RHEED c(2x6) (1x3) c(2x10) Houze (2007) Resch-Esser (1997) Barvosa-Carter (2000) c(2x6) (1x3)

46 2D G a S b(001) ( H o g a n) Surface optical spectra for c(2x6) Houze et al., (2007) All previous structures fail to reproduce correctly the experimental RA spectra

47 2D G a S b(001) (H o g a n ) New structure: Second layer Ga 'doping' Electron counting rule fulfilled (1 Ga per (2x6) unit) Low energy, semiconducting surface (stable at 500C?) Better agreement with RA spectra True surface based on long chains with interruptions

48 Ab-initio Finite-Temperatures Excitons A. Marini Phys. Rev. Lett. 101, (2008) BSE is solved, in ab-initio manner, including the coupling with the lattice vibrations. E-ph interaction is treated in the Heine, Allen and Cardona approach. q k k k k p k p k p Exp. BSE

49 3D B io (G a rbuio -P ulc i) FORMAMIDE in water

50 0D : na no do ts Formation energy: Single- vs co-doping Si87H76 Si147H100 Largest possible distance Nearest neigbours Co-doping easier due to charge compensation No size dependence Cantele et al, Phys. Rev. B 72, (2005) S. Ossicini, F. Iori et al, Appl. Phys. Lett (2005) F. Iori, E. Degoli, S. Ossicini et al., J. Lum. (2006)

51 0D na no do ts Gap Homo-Lumo Eg decrease as nc s size increase Eg of codoped is shifted towards lower energies undoped codoped

52 0D na no do ts Absorption and Emission processes AbsorptionEmission E2 E3 Eabs Eem E4 E1 Excited state Ground state e-h pair

53 0D na no do ts (P ulc i-m a rs ili-p a lum m o ) Optical spectra within GW+BSE Si33BPH36 DFT Abs. (ev) 2.77 Emis. (ev) 1.78 Ψ exc ( re, rh ) 2 GW+BSE Stokes shift Hole fixed on B Electron localizes on P Agreement with experimental outcomes: With F. Iori et al PRB2007 M. Fujii, et al., Appl. Phys. Lett. 85, 1158 (2004)

54 PARIS (Reining) ROME (Del Sole) MILAN (Onida) YORK (Godby) LOUVAIN (Gonze) NANOQUANTA nnetwork of Excellence S.SEBASTIAN (Rubio) Nanoscale Quantum Simulations for Nanostructures and Advanced Materials BERLIN FHI (Scheffler) LUND (von Barth) JENA (Bechstedt) BERLIN FU (Gross)

55 MBPT/MM Method Application to indole in water solution

56 3D B io (G a rbuio -P ulc i) LIQUID WATER Liquid water = disordered system= huge unit cell 20 MD snapshots and average of results.

57 QM MM

58 3D B io (M o s c a C o nte-p ulc i) PHOTO-ISOMERIZATION OF RETINAL IN RHODOPSIN FIRSTS STEPS OF THE MECHANISMS OF VISION IN LIVING BEINGS Adriano Mosca Conte, Olivia Pulci, Rodolfo Del Sole, Leonardo Guidoni

59 3D B io (M o s c a C o nte-p ulc i) PHOTO-ISOMERIZATION OF RETINAL IN RHODOPSIN MINIMAL BASE MODEL Adriano Mosca Conte, Olivia Pulci, Rodolfo Del Sole, Leonardo Guidoni