Femtochemistry: Theory Investigators: Werner Jakubetz and Hans - - PowerPoint PPT Presentation

P9 - Femtochemistry: Theory 23 Sep 99: Slide 1

• Project part P9 -

Femtochemistry: Theory

• Investigators: Werner Jakubetz and Hans Lischka

Institut für Theoretische Chemie und Strahlenchemie Universität Wien

P9 - Femtochemistry: Theory 23 Sep 99: Slide 2

What?

• Theoretical / computational investigations on the

preparation, dynamics and control of molecular wavepackets and on the potential energy surfaces and couplings governing their motions

• Photochemistry
• Ultrafast molecular processes
• Dynamics of molecules in ‘unusual’ states
• New phenomena:

Wavepackets in ground states, polyatomics, bulk matter

P9 - Femtochemistry: Theory 23 Sep 99: Slide 3

Why?

• Control of molecules and molecular processes,

including chemical reactions

• Probing of molecular systems in the time-domain
• Guidance and interpretation of experiments
• Relations to wavepacket-related phenomena in a

wider ‘molecular‘ connotation

• Semiconductors

P9 - Femtochemistry: Theory 23 Sep 99: Slide 4

How?

• Ab initio quantum chemistry
• COLUMBUS program system

Vienna Univ - Ohio State Univ- Argonne Natl Lab

• Analytic gradients and nonadiabatic coupling elements
• Quantum and classical nuclear dynamics
• Wavepacket propagation
• Time-dependent Schrödinger equation
• Mixed quantum-classical techniques
• Optimal and Coherent Control algorithms

P9 - Femtochemistry: Theory 23 Sep 99: Slide 5

What is new?

• New insights
• Novel techniques
• Balanced description of many (>10) electronic states
• MRCI conical intersection location
• Ab initio dynamics
• New Standards
• The recurrent theme in computational chemistry:

striving for unprecedented levels of accuracy

• Evolution of models from simplistic to realistic

P9 - Femtochemistry: Theory 23 Sep 99: Slide 6

Acetylene - Focal point and paradigm

• Wavepacket dynamics and PES
• Interferometry, recurrences, revivals
• Intramolecular coupling
• Arrest bend, uncouple stretches
• Photodissociation and PES
• Conical intersection
• Non-adiabatic dynamics
• Control of Photodissociation
• Electronic branching ratio
• Bond (isotope) selectivity

From Peric et al. (1984) From Cui et al. (1996)

P9 - Femtochemistry: Theory 23 Sep 99: Slide 7

Embedding and synergies

• Close contact and collaboration with P8

Strong mutual stimulation

• SRP-induced link to P4, P5, P7, P15

Common phenomenology

• Actual example: P4/P7

Multisubband wavepackets in quantum wells and coherent control

• cf. Tamborenea and Metiu (1999)
• Conceptual link to P2, P11
• New long-terms challenges
• cf. Corkum (1996, 1999)

P9 - Femtochemistry: Theory 23 Sep 99: Slide 8

Cooperations

• Within SRP

P8: established and working P7: envisaged

• External
• Long-standing international cooperations

Manchester, Berlin, OSU, Argonne, Budapest

• New, and already established

Weizmann* (Shapiro, Averbukh), Johns Hopkins (Yarkony)

• Wanted

Heidelberg, Emory, Experimental contacts (Zürich)

P9 - Femtochemistry: Theory 23 Sep 99: Slide 9

Ab initio quantum chemistry: Achievements and goals

• Balanced calculation of multi-state systems

(valence plus Rydberg states)

• π -systems
• New level of accuracy for location of conical

intersections

• PESs for photochemical processes
• Benchmark quality results for selected systems

P9 - Femtochemistry: Theory 23 Sep 99: Slide 10

Wavepacket dynamics: Achievements and goals

• Nonadiabatic dynamics of molecular collisionms
• Control of molecular processes (small systems)
• Simulations of wavepacket interferometry
• Ab initio dynamics based on accurate PES and

nonadiabatic couplings

• From small to complex
• From gas-phase molecules to other forms of

molecular matter