TY - CHAP A1 - Bonačić-Koutecký, Vlasta A1 - Hartmann, Michael A1 - Pittner, Jiřı́ A1 - Dam, Huub van ED - Barone, Vincenzo ED - Bencini, Alessandro ED - Fantucci, Piercarlo T1 - Theoretical exploration of single and multi state femtosecond nuclear dynamics of small metallic clusters using the DF method T2 - Recent Advances in Density Functional Methods: Part 3 N2 - Keine Angabe - No details KW - Nuclear dynamics KW - Metallic clusters KW - DF method Y1 - 2000 N1 - Volltext aus urheberrechtlichen Gründen nicht verfügbar. Fulltext due to copyright not available. SP - Keine Angabe - No details EP - Keine Angabe - No details PB - World Scientific CY - Singapore ER - TY - JOUR A1 - Andrianov, Igor A1 - Bonačić-Koutecký, Vlasta A1 - Hartmann, Michael A1 - Manz, Jörn A1 - Pittner, Jiřı́ A1 - Sundermann, K. T1 - Ab initio three-dimensional quantum dynamics of Ag3 clusters in the NeNePo process JF - Chemical Physics Letters N2 - The first three-dimensional quantum-dynamical ab initio simulation of the large amplitude vibrational dynamics of an Ag3 cluster initiated from its linear transition state is presented. This can be monitored by femtosecond pump-probe negative-ion to neutral-to-positive-ion spectroscopy with zero electron kinetic energy (NeNePo-ZEKE). The time evolution of the representative wavepacket confirms the dynamical effects which have been discovered previously by Wigner-type semiclassical simulations: the initial coherent bending and stretching from linear to near equilateral triangular configuration, followed by intracluster collision and intracluster vibrational relaxation with a weak fractional revival. In addition, the quantum wavepacket shows interferences and spreading. KW - Chemical physics KW - Three dimensional quantum dynamics Y1 - 2000 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:0298-opus4-5637 VL - 318 IS - 1-3 SP - 256 EP - 262 ER - TY - JOUR A1 - Hartmann, Michael A1 - Pittner, Jiřı́ A1 - Dam, Huub van A1 - Veyret, Vincent A1 - Bonacic-Koutecký, Vlasta T1 - Theoretical exploration of stationary and of ultrafast spectroscopy of small clusters JF - Applied Physics B N2 - Stationary spectra offer information on the interplay between the structures and the nature of electronic excitations reflecting bonding properties, as shown by comparing Sin with Agn (n=4-6) clusters. In order to study the dynamical properties, simulations and analysis of femtosecond (fs) time-resolved pump–probe or pump–dump signals have been carried out, which allows us to determine the timescales and the nature of configurational changes versus internal vibrational relaxation (IVR) in electronic ground or excited states. For this purpose we have developed a multi-state ab initio molecular dynamics (involving ground as well as adiabatic or non-adiabatic excited electronic states) on the timescale of the nuclear motion, using the time evolution of a thermal ensemble in the Wigner representation. The combination of ab initio quantum-chemical methods used for the molecular dynamics ‘on the fly’ and the Wigner-distribution approach for the description of the motion of the nuclei also allowed the accurate determination of pump–probe and pump–dump signals under temperature-dependent initial conditions. We use this novel combination of methods to investigate the dynamics in excited states of non-stoichiometric NanFn-1 clusters with a single excess electron. The timescales of the structural relaxation in excited states versus intramolecular vibrational relaxation processes have been determined, as illustrated for the example of Na4F3. This is the first study of the system with 15 degrees of freedom for which the dynamics in the excited states has been carried out without the precalculation of the energy surfaces. KW - Physics KW - Laser technology KW - Engineering Y1 - 2000 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:0298-opus4-5693 VL - 71 IS - 3 SP - 343 EP - 349 ER -