Adsorption calculated potential energy surface

Olsen R A, Philipsen P H T, Baerends E J, Kroes G J and Louvik O M 1997 Direct subsurface adsorption of hydrogen on Pd(111) quantum mechanical calculations on a new two-dimensional potential energy surfaced. Chem. Phys. 106 9286... 

The last years have witnessed tremendous progress in the theoretical description of surfaces and processes on surfaces. A variety of surface properties can now be described from first principles, i.e. without invoking any empirical parameters [1], In particular, whole potential energy surfaces (PES) can nowadays be mapped out by total energy calculations based on ab initio electronic structure theory. This development has also motivated new efforts in the dynamical treatment of adsorption/desorption processes in the last decade such as the development of efficient schemes for high-dimensional quantum dynamical simulations [2, 3]. 

The reliability of high-dimensional quantum calculations based on ab initio potential energy surfaces is also demonstrated in Fig. 6, where the sticking probability of H2/Cu(l 0 0) obtained by sixdimensional wave packet calculations [32] is compared to experimental results derived from an analysis of adsorption and desorption experiments [27]. The measured experimental sticking probabilities and, via the principle of detailed balance, also desorption distributions had been fitted to the following analytical form of the vibrationally resolved sticking probability as a function of the kinetic energy ... 

The NRL tight-binding method has been used to address the adsorption of 02 on Pt(l 1 1) [99]. The Pt-Pt interactions were taken from a large data base of TB parameter for the elements which are posted on the world wide web [100]. These parameters were obtained from a fit to DFT bulk calculations. Still, it has been demonstrated that the pure Pt surface is also well-described by this parametrization [42], For the Pt-O and the 0-0 TB parameters a new fit had to be performed. They were adjusted in order to reproduce the GGA-DFT results of the 02/Pt(l 1 1) potential energy surface [91, 92], The root mean square error of the fit is below 0.1 eV [41] which is in the range of the error of the GGA-DFT calculations. The spin state of the oxygen molecule was not explicitly considered in the... 

Theoretical methods are required to derive structural information from spectroscopic data, which usually concern measurements of electronic features. Because of the availability of large and efficient computer power and the current state of the art of theoretical chemistry, electronic structure calculations on model systems of relevance to experimental studies can be made. In addition, the catalytic chemist needs insight into the factors that determine the transition-state potential energy surface of reacting molecules. Also methods are needed to predict the geometry of the adsorption site as a function of metal surface composition or charge distribution in the zeolite. These methods will be extensively discussed in the next chapters. 

In the present work, we report DFT calculations of hydrocarbons adsorption on Au2o cluster [4]. All calculations were carried out with the nonempirical local PBE (Perdew—Burke—Ernzerhof) functional, which we have used earlier in the study of gold complexes [5]. Calculations were performed with a PRIRODA software [6]. The basis set with the SBK pseudopotential was used [7]. In this pseudopotential, the outer electronic shells are described by the following basis sets H [311/1], C [311/311/11] and Au [51111/51111/5111]. The types of stationary points on potential energy surfaces were determined from analysis of Hessians. The second derivatives were calculated analytically. 

Similarly, Wang et al. [50] used B3LYP functional to study the adsorption and decomposition of the radical OOH and H2O2 on Pt clusters (Pt3, Pt4, Ptg, and Ptio). The potential energy surface for the complete reduction of oxygen in acidic medium has been calculated (Fig. 11.5). They foimd that the OOH radical has a very strong adsorption on Pt clusters. Both thermodynamics and kinetics indicate... 

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