Dresden 2003 – wissenschaftliches Programm

Bereiche | Tage | Auswahl | Suche | Downloads | Hilfe

SYCN: Computational nanoscience - from materials to biology

SYCN 102: Computational Nanoscience: From Materials to Biology (Poster, gemeinsam mit SYSE)

SYCN 102.9: Poster

Dienstag, 25. März 2003, 19:00–21:00, ZEU/160

Hydrogen bonded systems: A comparative DFT study — •L. Ismer, J. Ireta, and J Neugebauer — Faradayweg 4-6, D-14195 Berlin

As Hydrogen bonds (hb) and proton transfer (pt) play a key role for the functionality of biomolecules, they have to be described accurately to adequately simulate such systems. We therefore performed a comparative DFT study on various hydrogen bonded benchmark systems by determining hb strengths, pt barriers, atomic geometries and vibrational frequencies, using i) the PBE-functional and, stimulated by recent reports, ii) the PBE-LDA-functional (exchange from PBE, correlation from LDA). We find that PBE gives accurate hb strengths (error   1 kcal/mol) but underestimates pt barriers by   5 kcal/mol. Although this error is reflected in the geometries and vibrations, the deviations for the zero-point corrections are generally rather small (  0.5 kcal/mol). For PBE-LDA we found improved pt barriers (error   2 kcal/mol), vibrations and geometries but hb strengths are underestimated by   2 kcal/mol. Based on this approach we calculated the vibrations and the free energy of an inifinite polyalanine a-helix and compared our results with experiment.