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New pump-dump optimal control strategy applicable to the systems of moderate complexity has been developed which allows to drive the system to the desired objective in the ground state via electronically excited state. The strategy is based on the concept of the intermediate target in the excited state whose role is to select appropriate Franck-Condon window at a given time delay between pump and dump pulses in order to reach optimally the objective. The concept was applied on the isomerization process in Na3F2 employing our ab initio Wigner distribution approach. The pump and dump pulses have been found which suppress the radiationless transition through the conical intersection and drive the system via electronically excited state to the second isomer in the ground state with the maximal yield. [ABSTRACT FROM AUTHOR]

Bimetallic silver-gold clusters are well suited to study changes in metallic versus “ionic” properties involving charge transfer as a function of the size and the composition. We present structures, ionization potentials (IP) and vertical detachment energies (VDE) for neutral and charged bimetallic AunAgm ( 2≤(n + m)≤5) clusters obtained from density functional level of theory. In the stable structures of these clusters Au atoms assume positions which favor charge transfer from Ag atoms. In clusters with equal numbers of hetero atoms (n = m = 1- 4) heteronuclear bonding is preferred to homonuclear bonding, giving rise to large values of ionization potentials. For larger clusters (n=m=5, 10) stable structures do not favor neither hetero bonding nor segregation into the single components, although they exhibit more metallic than ionic features. This remains valid also for Au8Ag12 cluster characterized by strong charge transfer to gold subunit. The influence of doping of pure gold clusters with silver atoms on VDE and IP values is discussed in context of their reactivity towards O2 and CO molecules. As a starting point we consider reactivity towards CO and O2 molecules on the example of AgAu- dimer. The results show that the catalytic cycle can be fullfilled. [ABSTRACT FROM AUTHOR]

Density functional calculations have been performed for the V2O5+ reactions towards ethylene considering atomic and molecular oxygen loss, oxygen transfer and association reactions. The oxygen transfer channel to ethylene is energetically favourable in contrast to the oxygen loss. This is in agreement with the experimental results [1] which show that V2O–+ does not lose atomic oxygen during the collision induced dissociation at thermal energies. A radical cation mechanism based on structure-reactivity relation of V2O5+ cluster is proposed to explain oxygen transfer channel indicating that this reaction is size selective. [ABSTRACT FROM AUTHOR]

The ab initio molecular dynamics (AIMD) [1] is combined with the heuristic, successive confinement method of surveying a potential energy surface (PES) [2], thereby offering a framework for the simulation study of kinetics and equilibrium properties of metallic clusters. This approach is applied to the study of Au4, a cluster possessing a simple but specific PES, which consists of very shallow and deep basins and due to this presents a challenge to the conventional AIMD methods. Among other things, the probabilities of the transitions between isomers have been found, and on this basis, both the time-dependent and equilibrium populations of the isomers have been calculated for the conditions typical of the NeNePo experiments [3] in the femtosecond pump-probe spectroscopy. [ABSTRACT FROM AUTHOR]

The ab initio molecular dynamics (AIMD) [1] is combined with the heuristic, successive confinement method of surveying a potential energy surface (PES) [2], thereby offering a framework for the simulation study of kinetics and equilibrium properties of metallic clusters. This approach is applied to the study of Au4, a cluster possessing a simple but specific PES, which consists of very shallow and deep basins and due to this presents a challenge to the conventional AIMD methods. Among other things, the probabilities of the transitions between isomers have been found, and on this basis, both the time-dependent and equilibrium populations of the isomers have been calculated for the conditions typical of the NeNePo experiments [3] in the femtosecond pump-probe spectroscopy. [ABSTRACT FROM AUTHOR]