TY - CHAP A1 - Ternès, Anabel T1 - Communication Conflicts and Social Media: on the Communication Culture of Contributors in Social Media Platforms T2 - 2nd Global Conference Commmunication & Conflict, Salzburg N2 - Keine Angabe - No details KW - Communication KW - Social media Y1 - 2012 N1 - Volltext aus urheberrechtlichen Gründen nicht verfügbar. Fulltext due to copyright not available. ER - TY - JOUR A1 - Gockel, Christine A1 - Kerr, Norbert L. T1 - Put-Down Humor Directed at Outgroup Members Increases Perceived - But Not Experienced - Cohesion in Groups JF - Humor: International Journal of Humor Research N2 - Put-down humor always has a target, and the intent of the speaker is to make fun of someone or something. Due to its inherently social nature, put-down humor could strongly affect socio-emotional group processes and outcomes like cohesion. We hypothesized that put-down humor would increase cohesion when it was targeted at outgroup members and was followed by laughter. Two laboratory experiments were conducted to examine the underlying processes of the put-down humor – cohesion relation. Study 1 showed that put-down humor of outgroup members (as compared to no humor) did not increase participants’ attraction to the group. But it increased perceived cohesion among other group members and the perception that other group members felt safer and were more similar to each other. Even when procedures were altered in Study 2 to reduce participants’ evaluation apprehension and their potential anxiety about not themselves being humorous, we found the same pattern of results. We discuss which conditions might be necessary for put-down humor to increase one’s personal attraction to a group. KW - Put-down Humor KW - Study Y1 - 2015 N1 - Online: https://www.researchgate.net/publication/276139334_Put-Down_Humor_Directed_at_Outgroup_Members_Increases_Perceived_-_But_Not_Experienced_-_Cohesion_in_Groups VL - 28 IS - 2 SP - 205 EP - 228 ER - TY - JOUR A1 - Meyer, Bertolt A1 - Schermuly, Carsten C. A1 - Kauffeld, Simone T1 - That’s not my place: the interacting effects of faultlines, subgroup size, and social competence on social loafing behaviour in work groups JF - European Journal of Work and Organizational Psychology N2 - Taking a social relations approach to team diversity, we propose that faultlines—hypothetical dividing lines that split a team into relatively homogeneous subgroups—impact the team members’ propensity to exhibit social loafing behaviour. We further propose that this individual-level reaction to the faultline structure of the team can differ among team members, depending on the size of their subgroup and on their individual social competence. We tested the assumptions with a sample of real teams working on an intellective task during which social loafing behaviour was video-coded. In partial support of the hypotheses, generalized mixed models revealed that social loafing behaviour was most common for team members who were part of a team with strong faultlines, who belonged to the larger subgroup in their team, and who exhibited low levels of social competence. The results therefore highlight the benefits of taking a multilevel approach to the effects of faultlines. KW - Faultlines KW - Subgroups KW - Social Loafing KW - Social Competence KW - Team Diversity Y1 - 2015 N1 - Online: https://www.researchgate.net/publication/270584492_That%27s_not_my_place_The_interacting_effects_of_faultlines_subgroup_size_and_social_competence_on_social_loafing_behavior_in_work_groups VL - 25 IS - 1 SP - 31 EP - 49 ER - 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 - Bonačić-Koutecký, Vlasta T1 - Theoretical study of femtosecond pump–probe signals of nonstoichiometric alkali halide clusters JF - The European Physical Journal D N2 - We present the outline of the ab–initio molecular dynamics method for adiabatic excited states which is suitable to treat the involved excited electronic states simultaneously with the motion of the nuclei. The method allows the simulation of time–resolved pump–probe signals and the analysis of the signals in terms of the underlying nuclear dynamics. Moreover, the timescales of the structural relaxation in excited electronic states vs. intramolecular vibrational relaxation processes can be estimated and the influence of the initial temperature of the cluster can be determined. The method is applied to the analysis of the timescales as well as of the dynamics of localized/delocalized electronic excitations in the Na2F molecule which represents a test example for nonstoichiometric alkali–halides with one excess electron. The aim is to develop a method for the investigation of time–dependent laser induced processes in clusters which is capable to extract the leading physical effects responsible for the controlled excitation dynamics and for the evolution of the non–equilibrium states. KW - Physics KW - Optical physics KW - Molecular physics Y1 - 1999 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:0298-opus4-5640 VL - 9 IS - 1 SP - 393 EP - 397 ER - TY - JOUR A1 - Hartmann, Michael A1 - Heidenreich, Andreas A1 - Pittner, Jiřı́ A1 - Bonačić-Koutecký, Vlasta A1 - Jortner, Joshua T1 - Ultrafast Dynamics of Small Clusters on the Time Scale of Nuclear Motion JF - The Journal of Physical Chemistry A N2 - We present a theoretical study of the multistate dynamics of the Ag3-/Ag3/Ag3+ system on the time scale of nuclear motion, as explored by femtosecond pump−probe negative ion-to neutral-to positive ion (NENEPO) spectroscopy. The dynamics of the Ag3 cluster initiated from its linear transition state involves configurational relaxation, intracluster collision, and onset of IVR, resonant and dissipative IVR and vibrational equilibration, whose time scales were determined. Our analysis reveals that theory is essential for the elucidation of the rich dynamic information regarding geometrical change, completion of IVR, and vibrational coherence effects in the NENEPO femtosecond signals. KW - Physical chemistry KW - Nuclear motion Y1 - 1998 N1 - Volltext aus urheberrechtlichen Gründen nicht verfügbar. Fulltext due to copyright not available. VL - 102 IS - 23 SP - 4069 EP - 4074 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 - TY - JOUR A1 - Bonačić-Koutecký, Vlasta A1 - Hartmann, Michael A1 - Pittner, Jiřı́ A1 - Dam, Huub van T1 - Theoretical exploration of ultrafast spectroscopy of small clusters JF - International Journal of Quantum Chemistry N2 - The central issue in femtosecond (fs) time resolved spectroscopy of clusters is the investigation of geometric relaxation and internal vibrational redistribution (IVR) after optical excitation in a nonequilibrium configuration of nuclei by laser photoelectron excitation, and corresponding time delayed probing by multiphoton-ionization. For this purpose, we have developed multistate ab initio molecular dynamics involving adiabatic ground and excited electronic states, as well as nonadiabatic coupling between them, using the time evolution of initial thermal ensemble in Wigner representation. The combination of ab initio quantum chemical methods, used for the adiabatic and nonadiabatic molecular dynamics “on the fly,” and the Wigner distribution approach for the description of the motion of the nuclei allowed us the accurate determination of pump-probe and pump-dump signals also under temperature dependent initial conditions. The connection between simulated pump-probe signals and the underlying dynamics of nuclei involving adiabatic electronic ground states has been first established for the example of the Agequation image/Ag3/Agequation image systems, and compared with experimental negative-to-neutral-to-positive NeNePo pump-probe signals. Our simulations reproduced the experimental NeNePo results and determined, in addition to the timescales of geometric relaxation, the conditions under which the resonant or dissipative IVR, as well as vibrational coherence, should be found in the experimental pump-probe signals. This can be realized in the zero electron kinetic energy NeNePo-ZEKE experiments, which are in progress. The above combination of methods has been recently extended to the analysis of the timescales as well as of the dynamics in excited electronic states of the nonstoichiometric NanFn−1 (n=2–4) clusters with the single excess valence electron. Our approach allows the simulation of femtosecond NeExPo-pump-probe and NeExNe-pump-dump signals, based on an analytic formulation which utilizes temperature dependent ground state initial conditions of neutral system (Ne); an ensemble of trajectories carried out either on the adiabatic electronic excited state (Ex), or on both the excited and the ground states through nonadiabatic coupling in connection with the fewest switching hopping algorithm for the investigation of the dynamics of the system; and either the cationic (Po) or the neutral ground state (Ne) for the probing step. The choice of the systems has been made in order to determine the timescales of processes involving (1) fast geometric relaxation leaving the bonding frame intact versus IVR, as during the adiabatic dynamics in the first excited state of Na4F3, being the smallest prototype of F-colored centers in the bulk; and (2) the photo-isomerization process through the conical intersection during nonadiabatic dynamics due to the long amplitude motion, as in the Na3F2 cluster after breaking of one metallic and one ionic bond, representing the first example of a five atomic cluster in the gas phase exhibiting conical intersection between the ground and the first excited state. In both cases, full complexity of the problem has been considered taking into account all degrees of freedom. The investigated systems represent important test cases for providing the conceptual framework of ultrafast dynamics in finite systems. KW - Quantum chemistry KW - Ultrafast spectroscopy Y1 - 2001 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:0298-opus4-5712 VL - 84 IS - 6 SP - 714 EP - 739 ER - TY - JOUR A1 - Hartmann, Michael A1 - Pittner, Jiřı́ A1 - Bonačić-Koutecký, Vlasta A1 - Heidenreich, Andreas A1 - Jortner, Joshua T1 - Theoretical exploration of femtosecond multi-state nuclear dynamics of small clusters JF - The Journal of Chemical Physics N2 - We investigate ultrafast multi-state nuclear dynamics in a triatomic cluster. In particular, we explore how the intracluster nuclear dynamics of the Ag−3/Ag3/Ag+3 system is reflected in the femtosecond pump-probe negative ion-to neutral-to positive ion (NENEPO) signals. The nuclear dynamics is based on classical trajectories on the ground electronic adiabatic state potential hypersurfaces obtained from accurate ab initio quantum chemistry calculations. The nuclear dynamics of Ag3 initiated from the linear transition state involves distinct sequential processes of configurational relaxation to the triangular configuration, intracluster collisions, and the onset of IVR, resonant, and dissipative IVR, and vibrational equilibration. We determined the timescales for these processes and discussed their dependence on the initial cluster temperature. The Wigner representation of the density matrix was utilized to simulate the NENEPO-zero kinetic energy (NENEPO-ZEKE) signal and the total (integrated over the photoelectron energy) NENEPO signal. We show how geometrical change, completion of IVR and vibrational coherenceeffects can be identified in the NENEPO signals. A comparison of the calculated NENEPO signals with the available experimental data is presented. KW - Cluster dynamics KW - Femtosecond dynamics Y1 - 1998 N1 - Volltext aus urheberrechtlichen Gründen nicht verfügbar. Fulltext due to copyright not available. VL - 108 IS - 8 SP - 3096 EP - 3113 ER - TY - CHAP A1 - Schreiber, Michael A1 - Hartmann, Michael T1 - Numerical Study of the Photoexcitation of Solitons in Conjugated Polymers T2 - 3rd International conference on excitonic processes in condensed matter (EXCON '98) N2 - Keine Angabe - No details KW - Excitonic processes KW - Condensed matter KW - EXCON Y1 - 1998 N1 - Online: http://books.google.de/books?id=eRhkFFqeWDUC&pg=PA71&lpg=PA71&dq=Numerical+Study+of+the+Photoexcitation+of+Solitons+in+Conjugated+Polymers&source=bl&ots=qUrItz2xA5&sig=M_kSx03VP1h1OOe_KGkel8BJnB4&hl=de&sa=X&ei=q2K1U_CBAqf54QSAlYCgDA&ved=0CC8Q6AEwAQ#v=onepage&q=Numerical%20Study%20of%20the%20Photoexcitation%20of%20Solitons%20in%20Conjugated%20Polymers&f=false ER - TY - JOUR A1 - Bonačić-Koutecký, Vlasta A1 - Pittner, Jiřı́ A1 - Pou-Amérigo, Rosendo A1 - Hartmann, Michael T1 - Ab-initio study of structural and optical properties of nonstoichiometric alkalimetal- oxides JF - Zeitschrift für Physik D N2 - Structural and optical properties of nonstoichiometric LinO and NanO (n = 3, 4) clusters containing one and two excess electrons are studied using ab-initio methods accounting for electron correlation. We show that calculated absorption patterns are excellent fingerprints of structural and bonding properties. The optical response of Li4O and Na4O clusters with the most stable tetrahedral type structures is characterized by a common feature, that is the appearance of a dominant intense transition in infrared regime although excess of electrons are not localized, as it is the case for small alkali-halide clusters, with cuboid corner vacancy (surface F-center in finite systems). KW - Inorganic Chemistry KW - Physical chemistry Y1 - 1997 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:0298-opus4-5748 VL - 40 IS - 1 SP - 445 EP - 447 ER - TY - JOUR A1 - Röseler, J. A1 - Hartmann, Michael T1 - An exactly solvable model for the large polaron JF - Zeitschrift für Physik B N2 - We present an exactly diagonalizable model Hamiltonian for the large polaron derived by analyzing the variational ansatz by Haga-Larsen (HL) for the Fröhlich Hamiltonian. The lowest energy eigenvalue of the model Hamiltonian for fixed wave numbers reproduces the energy of the variational ansatz by Haga-Larsen and is, therefore, an upper bound with respect to the corresponding energy eigenvalue of the Fröhlich Hamiltonian. This is valid for any momentum which is proven by extending the Haga-Larsen approach. Furthermore, since all integrations can be performed analytically, the model Hamiltonian is easily tractable. The energy eigenvalue spectrum of the model Hamiltonian is studied below and above the phonon-emission threshold. The quality of the model Hamiltonian is determined by the variational ansatz of Haga and Larsen. Incorporating an improved energy-momentum relation, a generalized model Hamiltonian is derived possessing a larger validity range with respect to the coupling strength. Furthermore, a second exactly diagonalizable model Hamiltonian based on improved Wigner-Brillouin perturbation theory due to Warmenbol, Peeters, and Devreese (WPD) is presented. It is briefly demonstrated that one is able to construct all mentioned model Hamiltonians also in the 2D polaron problem. In contrast to the 3D case, where the HL-type model Hamiltonian possesses the higher quality for any momentum, in the 2D case, it works well only for small momenta. For large momenta, only the WPD-type model Hamiltonian describes the energy-momentum relation correctly. We demonstrate the usefulness of the model Hamiltonian concept by exactly calculating the one-electron Green’s function for all mentioned model Hamiltonians and comment why significant advantages of the model Hamilton concept for the treating of low-dimensional systems (planar semiconducting quantum-well structures) can be expected. KW - Inorganic Chemistry KW - Engineering KW - Condensed Matter Physics Y1 - 1997 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:0298-opus4-5782 VL - 102 IS - 4 SP - 531 EP - 540 ER - TY - JOUR A1 - Hartmann, Michael A1 - Schreiber, Michael A1 - Streitwolf, H.-W. A1 - Mukamel, Shaul T1 - Nonlinear optical excitations in femtosecond spectroscopy of conjugated polymers JF - Journal of Luminescence N2 - We have investigated the optical excitation of solitons and charge transfer excitons in polymer chains by solving the equations of motion for the reduced density matrix and the lattice displacement simultaneously in time. Electron-phonon coupling leads to polaron-exciton formation which can be identified in transient pump-probe signals. KW - Optical excitation KW - Femtosecond spectroscopy KW - Conjugated polymers Y1 - 1995 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:0298-opus4-5795 VL - 66-67 SP - 97 EP - 101 ER -