@article{HuberKlamroth2005,
  author    = {Huber, C. and Klamroth, Tillmann},
  title     = {Simulation of two-photon-photoelectron spectra at a jellium-vacuum interface},
  year      = {2005},
  abstract  = {In this paper we report on time dependent configuration interaction singles (TD-CIS) calculations aimed at simulating two-photon-photoelectron emission (2PPE) spectra of metal films, the latter treated within a one-dimensional jellium model. The method is based on a many-electron approach in which electron-electron-scattering is approximately accounted for and no artificial lifetimes have to be assumed for excited electrons. This contrasts with one-electron models where lifetimes and "dissipation" have to be introduced. The driving force for the photoelectron ejection in 2PPE experiments is the electric field of two laser pulses that are generally separated by a delay time, Delta t. To compute energy- and time-resolved 2PPE signals P(E, Delta t), a new scheme based on the time-energy method is proposed to analyze electronic wave packets in asymptotic regions of the potential},
  language  = {en}
}
@article{NestKlamroth2005,
  author    = {Nest, Mathias and Klamroth, Tillmann},
  title     = {Correlated many-electron dynamics : application to inelastic electron scattering at a metal film},
  year      = {2005},
  abstract  = {The multiconfiguration time-dependent Hartree-Fock and the time-dependent configuration interaction singles method are applied to the correlated many-electron dynamics of a one-dimensional jellium model system. We study the scattering of an initially free electron at a model film in the framework of both approaches. In particular, both methods are compared with regard to how they describe the underlying physical processes, namely inelastic electron scattering, inverse photoemission, and electron impact ionization},
  language  = {en}
}
@article{KrauseKlamrothSaalfrank2005,
  author    = {Krause, Pascal and Klamroth, Tillmann and Saalfrank, Peter},
  title     = {Time-dependent configuration-interaction calculations of laser-pulse-driven many-electron dynamics : Controlled dipole switching in lithium cyanide},
  issn      = {0021-9606},
  year      = {2005},
  abstract  = {We report simulations of laser-driven many-electron dynamics by means of the time-dependent configuration interaction singles (doubles) approach. The method accounts for the correlation of ground and excited states, is capable of describing explicitly time-dependent, nonlinear phenomena, and is systematically improvable. Lithium cyanide serves as a molecular test system in which the charge distribution and hence the dipole moment are shown to be switchable, in a controlled fashion, by (a series of) laser pulses which induce selective, state-to-state electronic transitions. One focus of our time-dependent calculations is the question of how fast the transition from the ionic ground state to a specific excited state that is embedded in a multitude of other states can be made, without creating an electronic wave packet. (c) 2005 American Institute of Physics},
  language  = {en}
}
@article{AndrianovKlamrothSaalfranketal.2005,
  author    = {Andrianov, Igor V. and Klamroth, Tillmann and Saalfrank, Peter and Bovensiepen, U. and Gahl, Cornelius and Wolf, M. M.},
  title     = {Quantum theoretical study of electron solvation dynamics in ice layers on a Cu(111) surface},
  issn      = {0021-9606},
  year      = {2005},
  abstract  = {Recent experiments using time- and angle-resolved two-photon photoemission (2PPE) spectroscopy at metal/polar adsorbate interfaces succeeded in time-dependent analysis of the process of electron solvation. A fully quantum mechanical, two-dimensional simulation of this process, which explicitly includes laser excitation, is presented here, confirming the origin of characteristic features, such as the experimental observation of an apparently negative dispersion. The inference of the spatial extent of the localized electron states from the angular dependence of the 2PPE spectra has been found to be non-trivial and system-dependent. (C) 2005 American Institute of Physics},
  language  = {en}
}
@article{SaalfrankKlamrothHuberetal.2005,
  author    = {Saalfrank, Peter and Klamroth, Tillmann and Huber, C. and Krause, Pascal},
  title     = {Laser-driven electron dynamics at interfaces},
  issn      = {0021-2148},
  year      = {2005},
  abstract  = {In this paper we present time-dependent, quantum-dynamical simulations of photoinduced processes at solid surfaces involving nonadiabatic transitions of electrons to and from short-lived intermediate excited states. In particular, two-photon photoemission (2PPE) spectra of naked metal surfaces and free-standing metal films are considered. One major problem in both cases is the presence of electron-electron scattering, which is treated here in various ways. The first way is to adopt an open-system density matrix approach, in which a single electron is weakly coupled to a "bath" of other electrons. The second approach is based on a many-electron Schrodinger equation, which is solved with the help of a time-dependent configuration interactions singles (TD-CIS) method},
  language  = {en}
}
@article{NestKlamrothSaalfrank2005,
  author    = {Nest, Mathias and Klamroth, Tillmann and Saalfrank, Peter},
  title     = {The multiconfiguration time-dependent Hartree-Fock method for quantum chemical calculations},
  issn      = {0021-9606},
  year      = {2005},
  abstract  = {We apply the multiconfiguration time-dependent Hartree-Fock method to electronic structure calculations and show that quantum chemical information can be obtained with this explicitly time-dependent approach. Different equations of motion are discussed, as well as the numerical cost. The two-electron integrals are calculated using a natural potential expansion, of which we describe the convergence behavior in detail},
  language  = {en}
}
@article{KlamrothKronerSaalfrank2005,
  author    = {Klamroth, Tillmann and Kroner, Dominic and Saalfrank, Peter},
  title     = {Laser-driven coupled electron-nuclear dynamics : Quantum mechanical simulation of molecular photodesorption from metal films},
  issn      = {1098-0121},
  year      = {2005},
  abstract  = {In this paper we report dynamical simulations of laser-driven, coupled nuclear-electron dynamics for a molecule- surface system. Specifically, the laser desorption of a small molecule (NO) from a metal slab (Pt) in the so-called DIET limit (Desorption Induced by Electronic Transitions), is studied. The excitation of the metal electrons by a laser pulse followed by the formation of a negative ion resonance, its subsequent decay, and the simultaneous desorption of the molecule are all treated within a single quantum mechanical model. This model is based on an earlier theory of Harris and others [S. M. Harris, S. Holloway, and G. R. Darling, J. Chem. Phys. 102, 8235 (1995)], according to which a nuclear degree of freedom is coupled to an electronic one, both propagated on a single non-Born-Oppenheimer potential energy surface. The goals of the present contribution are (i) to make a conceptual connection of this model to the frequently adopted nonadiabatic "multi-state" models of photodesorption, (ii) to understand details of the desorption mechanism, (iii) to explicitly account for the laser pulse, and (iv) to study the photodesorption as a function of the thickness of the metal film, and the laser parameters. As an important methodological aspect we also present a highly efficient numerical scheme to propagate the wave packet in a problem-adapted diabatic basis},
  language  = {en}
}