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Car-Parrinello simulation of NH3 adsorbed on the MgO(100) surface

✍ Scribed by Walter Langel

Publisher: Elsevier Science
Year: 1996
Tongue: English
Weight: 603 KB
Volume: 259
Category: Article
ISSN: 0009-2614
DOI: 10.1016/0009-2614(96)00725-7

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✦ Synopsis

The Car-Parrinello method has been applied the adsorption of ammonia on regular (100) surfaces of solid magnesium oxide. One NH 3 molecule was positioned on a surface consisting of three layers with four Mg and four O atoms in each. The samples were first subjected to simulated annealing up to temperatures in the range of 50-300 K and then to a free molecular dynamics run covering time intervals of 2-3 ps. NH 3 is physisorbed on the surface. The N atom is bound to the Mg but not centered above it, The dynamics of the NH 3 molecule are discussed in terms of three modes, a stochastic reorientation of the molecule around its figure axis, a nutation around an axis vertical to the figure axis, and the N-H stretching modes. The calculation confirms recent inelastic neutron scattering results, which indicate rotation-translation coupling and a low barrier to the rotational motion.

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