IUVSTA 15th International Vacuum Congress (IVC-15), AVS 48th International Symposium (AVS-48), 11th International Conference on Solid Surfaces (ICSS-11)
    Surface Science Wednesday Sessions
       Session SS+SC-WeM

Paper SS+SC-WeM1
Empirical Density Functionals and the Adsorption of Organic Molecules on Si(100)

Wednesday, October 31, 2001, 8:20 am, Room 122

Session: Adsorption on Semiconductor and Metal Oxide Surfaces
Presenter: M.A. Phillips, The University of Nottingham, UK
Authors: M.A. Phillips, The University of Nottingham, UK
N.A. Besley, The University of Nottingham, UK
P.M.W. Gill, The University of Nottingham, UK
P. Moriarty, The University of Nottingham, UK
P.H. Beton, The University of Nottingham, UK
Correspondent: Click to Email
Density Functional Theory (DFT) has been used in the study of the adsorption of organic molecules such as ethene and ethyne for a number of years. Typically, for semiconductor surfaces, DFT methods are used in conjunction with a cluster model of the substrate.@footnote 1@ However, the computational expense of DFT calculations implies an upper limit on the size of the substrate model, and thus on the size of adsorbate molecule. As such, the study of larger adsorbates requires some reduction in computational expense, often leading to the use of parameterised semi-empirical methods. Unfortunately, such methods do not give good agreement with experiment for many semiconducting elements: another approach is required for these materials. The Empirical Density Functional, EDF1, has been shown to give very good agreement with values of atomisation energy, ionisation potential and proton affinity for the majority of species included in the G2 experimental data set.@footnote 2@ Furthermore, this functional does not require the evaluation of 'exact exchange' contributions, and is therefore significantly less computationally expensive than 'hybrid' functionals. However, the success of EDF1 in the determination of any other physio-chemical properties, in particular adsorption geometry, adsorption energy and vibrational structure, has never been tested. Here, we present the results from a density functional study of the adsorption of organic molecules on the Si(100) surface using EDF1, and discuss their validity through comparison to experimental measurements and results from equivalent calculations using the well known functional, B3LYP. We also compare the computational expense when using EDF1 in these calculations to that when B3LYP is used. @FootnoteText@ @footnote 1@ R. Konecný and D. J. Doren, Surf. Sci. 417 (1998), 169-188. @footnote 2@ R. D. Adamson, P. M. W. Gill and J. A. Pople, Chem. Phys. Lett. 284 (1998), 6-11.