نتایج جستجو برای: energy potential surface

تعداد نتایج: 2177097  

1997
Constantine Yannouleas Uzi Landman

We introduce a method of molecular dynamics in shape space aimed at metal clusters. The ionic degrees of freedom are described via a dynamically deformable jellium with inertia parameters derived from an incompressible, irrotational flow. The shell correction method is used to calculate the electronic potential energy surface underlying the dynamics. Our finite-temperature simulations of Ag14 a...

2009
Azzedine Lakhlifi John P. Killingbeck

Detailed semi-empirical interaction potential calculations are performed to determine the potential energy surface experienced by the molecules CO, HCN, H2O and H2CO, when adsorbed on the basal plane (0001) of graphite at low temperature. The potential energy surface is used to find the equilibrium site and configuration of a molecule on the surface and its corresponding adsorption energy. The ...

1997
Axel Gross Matthias Scheffler

The interaction of hydrogen with many transition metal surfaces is characterized by a coexistence of activated with non-activated paths to adsorption with a broad distribution of barrier heights. By performing six-dimensional quantum dynamical calculations using a potential energy surface derived from ab initio calculations for the system H2/Pd(100) we show that these features of the potential ...

1999
Andreas Eichler Jurgen Hafner Axel Groß Matthias Scheffler

By performing six-dimensional quantum-dynamical calculations on potential energy surfaces derived from density Ž . Ž . functional theory total-energy calculations, we have determined the sticking probability of H on Rh 100 , Pd 100 and 2 Ž . Ag 100 . In particular, we have focused on the dependence of the sticking probability on the initial rotational state of the impinging hydrogen beam. The d...

1999
James B. Anderson

The potential energy surface for the Hz-I2 system was determined in analytic variational electronic structure calculations with singleand double-substitution configuration interactions for the 16 valence electrons and with effective potentials for the iodine core electrons. The favored pathway for the overall reaction H,+I,d HI + HI was found to pass through the region of the collinear configur...

2002
R. Schinke D. Schwarzer

Recently, Wittig and co-workers have published rate coefficients kðEÞ for the unimolecular decomposition of photoinitiated NO2 close to the dissociation threshold [Chem. Phys. Lett. 358 (2002) 71]. They found out that kðEÞ for low angular momentum J exhibits a strong increase within 25 cm 1 of the reaction threshold. The authors emphasize that their experimental results are surprising and canno...

2004
Ludger Wirtz Michal Dallos Hans Lischka

We discuss the feasibility of the embedded cluster approach for ab-initio calculations of charge exchange between ions and a LiF surface. We show that the discrete density of valence states in embedded clusters converges towards the continuum limit of the density of states in the valence band of an infinitely extended LiF surface. Screening of the holes that are left in the surface after electr...

2003
H. Y. Mussa

The observation of an infrared spectrum of the H +3 molecular ion at its dissociation limit by Carrington and co-workers has presented a tremendous challenge to theory. To compute this spectrum it is necessary to model accurately the global potential energy surface of H +3 , vibrationally excited states at dissociation, rotational excitation, lifetimes of rotationally excited `shape’ resonances...

2006
M. Alducin H. F. Busnengo A. Salin

The dissociative adsorption of N2 on W(110) is studied using classical dynamics on a six-dimensional potential energy surface obtained from density functional theory calculations. Two distinct channels are identified in the dissociation process: a direct one and an indirect one. It is shown that the direct channel is inhibited for low energy molecules (Ei < 400 meV) and low incidence angles. Th...

2006
PAOLO BARLETTA JAMES J. MUNRO BRUNO C. SILVA J. Tennyson

Calculations are discussed which characterize all the vibrational bound states of the H3 and D2H C molecular ions using a realistic ab initio potential energy surface. Graphical analysis and calculation of rotational constants show that both ions support a series of atom–diatom-like long-range states: asymptotic vibrational states. The role of these states in the H3 system and other molecules i...

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