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

• 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 1

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 2

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 3

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 4

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 5

Acetylene - Focal point and paradigm • Wavepacket dynamics and PES • Interferometry, recurrences, revivals • Intramolecular coupling • Arrest bend, uncouple stretches From Peric et al . (1984) • Photodissociation and PES • Conical intersection • Non-adiabatic dynamics • Control of Photodissociation From Cui et al . (1996) • Electronic branching ratio • Bond (isotope) selectivity P9 - Femtochemistry: Theory 23 Sep 99: Slide 6

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 7

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 8

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 9

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 P9 - Femtochemistry: Theory 23 Sep 99: Slide 10