Münster 1999 – wissenschaftliches Programm

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CP: Chemische Physik

CP 31: Poster: Große Moleküle und Aggregate

CP 31.5: Poster

Montag, 22. März 1999, 18:00–20:00, R52/R72

Ab initio molecular-dynamics simulations of dye molecules on surfaces — •M. Sugihara¹, H. Meyer², P. Entel¹, V. Buss³, S. Falzewski³, and J. Hafner⁴ — ¹Theoretische Physik, Universit"at Duisburg, Duisburg — ²MPI f"ur Polymerforschung, Mainz — ³Theoretische Chemie, Universit"at Duisburg, Duisburg — ⁴Theoretische Physik, TU Wien, Wien

We have performed ab initio total energy calculations and molecular-dynamics simulations of dye molecules in water and on surfaces. With respect to photochemistry the study of the behavior of dye molecules on AgCl or AgBr surfaces would be of interest. Because of the many valence electrons of Ag we have investigated as a preliminary study the behavior of dye molecules on the NaCl(100) surface. We have simulated the flat dye molecule trimethin, [C₁₉H₁₇N₂O₂]⁺, which forms sandwich-like structures [1], and the cyanine molecule dimethylmethin, [C₂₁H₂₃N₂]⁺, which shows a typical stereochemical deformation due to two repulsive methyl groups. The molecular-dynamics simulations are able to reproduce the experimentally observed configuration of the charged molecules [2]. The behavior of trimethin, [C₇H₁₅N₂]⁺, in water has also been simulated. The calculations are using density functional theory with pseudopotentials and a plane-wave basis set as implemented in the Vienna ab initio simulation package (VASP) [3].

[1] V. Czikkely, H. D. F"orsterling, and H. Kuhn, Chem. Phys. Lett. 6, 11 (1970).

[2] H. Meyer, Y. Sakamoto, and P. Entel, to be published.

[3] G. Kresse and J. Hafner, Phys. Rev. B 49, 14 251 (1994).