@article{UtechtGaebelKlamroth2018,
  author    = {Utecht, Manuel Martin and Gaebel, Tina and Klamroth, Tillmann},
  title     = {Desorption induced by low energy charge carriers on Si(111)-7 x 7},
  series = {Journal of computational chemistry : organic, inorganic, physical, biological},
  volume    = {39},
  journal   = {Journal of computational chemistry : organic, inorganic, physical, biological},
  number    = {30},
  publisher = {Wiley},
  address   = {Hoboken},
  issn      = {0192-8651},
  doi       = {10.1002/jcc.25607},
  pages     = {2517 -- 2525},
  year      = {2018},
  abstract  = {We use clusters for the modeling of local ion resonances caused by low energy charge carriers in STM-induced desorption of benzene derivates from Si(111)-7 x 7. We perform Born-Oppenheimer molecular dynamics for the charged systems assuming vertical transitions to the charged states at zero temperature, to rationalize the low temperature activation energies, which are found in experiment for chlorobenzene. Our calculations suggest very similar low temperature activation energies for toluene and benzene. For the cationic resonance transitions to physisorption are found even at 0 K, while the anion remains chemisorbed during the propagations. Further, we also extend our previous static quantum chemical investigations to toluene and benzene. In addition, an in depth analysis of the ionization potentials and electron affinities, which are used to estimate resonance energies, is given.},
  language  = {en}
}
@article{Klamroth2006,
  author    = {Klamroth, Tillmann},
  title     = {Optimal control of ultrafast laser driven many-electron dynamics in a polyatomic molecule: N-methyl-6-quinolone},
  issn      = {0021-9606},
  doi       = {10.1063/1.2185633},
  year      = {2006},
  abstract  = {We report time-dependent configuration interaction singles calculations for the ultrafast laser driven many- electron dynamics in a polyatomic molecule, N-methyl-6-quinolone. We employ optimal control theory to achieve a nearly state-selective excitation from the S-0 to the S-1 state, on a time scale of a few (approximate to 6) femtoseconds. The optimal control scheme is shown to correct for effects opposing a state-selective transition, such as multiphoton transitions and other, nonlinear phenomena, which are induced by the ultrashort and intense laser fields. In contrast, simple two-level pi pulses are not effective in state-selective excitations when very short pulses are used. Also, the dependence of multiphoton and nonlinear effects on the number of states included in the dynamical simulations is investigated.},
  language  = {en}
}
@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}
}
@phdthesis{Klamroth2006,
  author    = {Klamroth, Tillmann},
  title     = {Quantum mechanical simulations for correlated many-electron dynamics and electron induced processes at surfaces},
  address   = {Potsdam},
  pages     = {206 S. : graph. Darst.},
  year      = {2006},
  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{Klamroth2003,
  author    = {Klamroth, Tillmann},
  title     = {Laser-driven electron transfer through metal-insulator-metal contacts : time-dependent configuration interaction singles calculations for a jellium model},
  issn      = {1098-0121},
  year      = {2003},
  abstract  = {In this paper we report time-dependent configuration interaction singles calculations modeling the laser- induced current through a metal-insulator-metal (MIM) contact. We compare our results to recent experiments [D. Diesing, M. Merschdorf, A. Thon, and W. Pfeiffer, Appl. Phys. B (to be published)]. We use two jellium slabs separated by a vacuum region in a one-dimensional model to describe the MIM contact. The contact is coupled to ultrashort (fs) laser pulses by the semiclassical dipole approximation. We discuss simulated two-pulse correlation spectra in comparison to experimental results},
  language  = {en}
}
@article{UtechtPalmerKlamroth2017,
  author    = {Utecht, Manuel Martin and Palmer, Richard E. and Klamroth, Tillmann},
  title     = {Quantum chemical approach to atomic manipulation of chlorobenzene on the Si(111)-7 x 7 surface},
  series = {Physical review materials},
  volume    = {1},
  journal   = {Physical review materials},
  number    = {2},
  publisher = {American Physical Society},
  address   = {College Park},
  issn      = {2475-9953},
  doi       = {10.1103/PhysRevMaterials.1.026001},
  pages     = {5},
  year      = {2017},
  abstract  = {We present a cluster model to describe the localization of hot charge carriers on the Si(111)-7 x 7 surface, which leads to (nonlocal) desorption of chlorobenzene molecules in scanning tunneling microscope (STM) manipulation experiments. The localized charge carriers are modeled by a small cluster. By means of quantum chemical calculations, this cluster model explains many experimental findings from STM manipulation. We show that the negative charge is mainly localized in the surface, while the positive one also resides on the molecule. Both resonances boost desorption: In the negative resonance the adatom is elevated; in the positive one the chemisorption bond between the silicon surface adatom and chlorobenzene is broken. We find normal modes promoting desorption matching experimental low-temperature activation energies for electron-and hole-induced desorption.},
  language  = {en}
}
@article{EhlertKlamroth2017,
  author    = {Ehlert, Christopher and Klamroth, Tillmann},
  title     = {The quest for best suited references for configuration interaction singles calculations of core excited states},
  series = {Journal of computational chemistry : organic, inorganic, physical, biological},
  volume    = {38},
  journal   = {Journal of computational chemistry : organic, inorganic, physical, biological},
  publisher = {Wiley-Blackwell},
  address   = {Hoboken},
  issn      = {0192-8651},
  doi       = {10.1002/jcc.24531},
  pages     = {116 -- 126},
  year      = {2017},
  abstract  = {Near edge X-ray absorption fine structure (NEXAFS) simulations based on the conventional configuration interaction singles (CIS) lead to excitation energies, which are systematically blue shifted. Using a (restricted) open shell core hole reference instead of the Hartree Fock (HF) ground state orbitals improves (Decleva et al., Chem. Phys., 1992, 168, 51) excitation energies and the shape of the spectra significantly. In this work, we systematically vary the underlying SCF approaches, that is, based on HF or density functional theory, to identify best suited reference orbitals using a series of small test molecules. We compare the energies of the K edges and NEXAFS spectra to experimental data. The main improvement compared to conventional CIS, that is, using HF ground state orbitals, is due to the electrostatic influence of the core hole. Different SCF approaches, density functionals, or the use of fractional occupations lead only to comparably small changes. Furthermore, to account for bigger systems, we adapt the core-valence separation for our approach. We demonstrate that the good quality of the spectrum is not influenced by this approximation when used together with the non-separated ground state wave function. Simultaneously, the computational demands are reduced remarkably. (C) 2016 Wiley Periodicals, Inc.},
  language  = {en}
}
@article{UtechtKlamroth2018,
  author    = {Utecht, Manuel Martin and Klamroth, Tillmann},
  title     = {Local resonances in STM manipulation of chlorobenzene on Si(111)-7x7},
  series = {Molecular physics},
  volume    = {116},
  journal   = {Molecular physics},
  number    = {13},
  publisher = {Routledge, Taylor \& Francis Group},
  address   = {Abingdon},
  issn      = {0026-8976},
  doi       = {10.1080/00268976.2018.1442939},
  pages     = {1687 -- 1696},
  year      = {2018},
  abstract  = {Hot localised charge carriers on the Si(111)-7x7 surface are modelled by small charged clusters. Such resonances induce non-local desorption, i.e. more than 10 nm away from the injection site, of chlorobenzene in scanning tunnelling microscope experiments. We used such a cluster model to characterise resonance localisation and vibrational activation for positive and negative resonances recently. In this work, we investigate to which extent the model depends on details of the used cluster or quantum chemistry methods and try to identify the smallest possible cluster suitable for a description of the neutral surface and the ion resonances. Furthermore, a detailed analysis for different chemisorption orientations is performed. While some properties, as estimates of the resonance energy or absolute values for atomic changes, show such a dependency, the main findings are very robust with respect to changes in the model and/or the chemisorption geometry. [GRAPHICS] .},
  language  = {en}
}
@article{KrausAschenbrennerKlamrothetal.2009,
  author    = {Kraus, Florian and Aschenbrenner, J{\"u}rgen C. and Klamroth, Tillmann and Korber, Nikolaus},
  title     = {Hydrogen polyphosphides P3H23- and P3H32- : synthesis and crystal structure of K3(P3H2)·2.3NH3, Rb3(P3H2)·NH3, [Rb(18-crown-6)]2(P3H3)·7.5NH3, and [Cs(18-crown-6)]2(P3H3)·7NH3},
  issn      = {0020-1669},
  doi       = {10.1021/Ic8014546},
  year      = {2009},
  abstract  = {The incongruous solvation of polyphosphides and phosphanes or the direct reduction of white phosphorus in liquid ammonia leads to the hydrogen polyphosphides catena-dihydrogen triphosphide, P3H23-, and catena-trihydrogen triphosphide, P3H32-, in the crystalline compounds K-3(P3H2)center dot 2.3NH(3) (1), Rb-3(P3H2)center dot NH3 (2), [Rb(18-crown-6)](2)(P3H3)center dot 7.5NH(3) (3), and [Cs(18-crown-6)](2)(P3H3)center dot 7NH(3) (4).},
  language  = {en}
}