Resumenes de las Charlas Invitadas
Atomic scale numerical simulations: Can we still use non «ab initio» electronic structure schemes?
Stepan Pick1 and Hugues Dreyssé 2
1 J. Heyrovsky Institute of Physical Chemistry, Academy of Sciences of the Czech republic,
Dolejskova 3, 182 23 Prague 8, Czech Republic
2 Institut de Physique et Chimie des Materiaux de Strasbourg,
23 rue du Loess, 67037 Strasbourg, France
Abstract
From the 70's, semi-empirical tight binding hamiltonians have been used widely in solid state
physics. If ab initio band structure formalisms as the venerable KKR or APW have been developed
before this date, the fantastic increase of the computational facilities has stimulated these last
twenty years the development of ab initio electronic structure schemes which are now routinely
used. In this talk will be presented few examples where can be seen the interest (and the limits)
of non ab initio frameworks. For instance in the case of light adsorbates (as C, N, O) or
molecules (as Nh3 or CO) on transition metal based nanostructures, the
semi-empirical tight binding scheme allows to consider complex arrangements of clusters which cannot
be yet described by ab initio schemes. In the case of the Magnetic Anisotropy Energy determination of
nanostructures, the semi empirical approach leads to a physical understandnis of the subtle oberved
behaviours. A major interest in the use of these non ab initio methods is to be able to obtain
general trends. In those both cases, will be addressed the answers given today by the ab initio
schemes.
Acknowledgements: This work has partially benefited of the Research Training Network
«Computational Magnetoelectronics» (N° HPRN-CT-2000-00143) of the
European Commission.
|
|