|
Internet Electronic Journal of Molecular Design - IEJMD, ISSN 1538-6414, CODEN IEJMAT
| ABSTRACT - Internet Electron. J. Mol. Des. May 2006, Volume 5, Number 5, 287-295 |
The Influence of the Basis Set Size on DFT Calculations of Surface
Complexes for the Assignment of SERS Spectra
Barbara Pergolese, Domenico Marchesan, Maurizio Muniz-Miranda, and Adriano Bigotto
Internet Electron. J. Mol. Des. 2006, 5, 287-295
|
Abstract:
DFT calculations of surface complex models are able to assist
the correct assignment of SERS spectra of compounds strongly
chemisorbed on metal surfaces. Till now these calculations have
been usually carried out using the LANL2DZ basis set on both
the metal and ligand atoms. Due to the reduced size of the
LANL2DZ basis set, the frequencies and the normal mode
description provided by them are not always accurate. Therefore,
the use of a mixed basis set can be a significant improvement in
these kinds of calculations. In the present paper we have reported
the results of an investigation of the influence of the basis set
size on the quality of calculations carried out on surface complex
models. The study has been performed on TZ3, because we have
already assigned its Raman and SERS spectra in silver colloids
with the help of DFT/LANL2DZ calculations. DFT/BPW91
calculations of the model of the surface complex formed by TZ3
on silver have been carried out with different mixed basis sets
varying the size of the basis used on the ligand. The quality of
the calculated results has been critically evaluated on the basis of
three important computational parameters: the absolute mean
delta, the standard deviation and the maximum delta. On the
basis of the comparison between all the calculations carried out
on the model of the surface complex formed by TZ3 on silver, it
has been evinced that the best basis set is the LANL2DZ/6-311+G.
|