Application of an approximate density-functional method to sulfur containing compounds

We present the results of an investigation of sulfur containing compounds u sing a tight-binding (TB) approach, which is a second-order approximation t o density-functional theory (DFT). The performance of the so-called self-co nsistent charge density-functional based TB (SCC-DFTB) method is analyzed v ia comparison of the results for several molecular properties with other se mi-empirical methods as well as with full DFT calculations. We also examine different conformers of the amino acid cysteine in order to estimate the r eliability of our method for large-scale biomolecular systems. We find that SCC-DFTB provides, in general, good agreement with full DFT calculations a nd a similar deviation from experiment. (C) 2001 Elsevier Science B.V. All rights reserved.