Regensburg 2002 – scientific programme

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SYBM: Physik biologischer Materie

SYBM 401: Physics of biological matter: Poster

SYBM 401.20: Poster

Tuesday, March 12, 2002, 18:00–19:30, H37

Theoretical and Experimental Analysis of Vibrational Properties of DNA Bases — •C.T. Crainic, A.Yu. Kobitski, R. Scholz, S. Silaghi, G. Salvan, T.U. Kampen, and D.R.T. Zahn — Institut für Physik, Technische Universität Chemnitz, 09107 Chemnitz, Germany

This work presents a theoretical insight into the electronic and vibrational properties of DNA bases, i.e. adenine, cytosine, guanine and thymine.

The electronic levels are obtained after the geometry optimization of isolated molecules performed with different methods (Hartree Fock and density functional methods). Different basis sets are used and compared.in this study. The accuracy of the methods is provided by means of the root-mean-square deviation between calculated and experimental frequencies of internal vibrational modes. The latter are obtained from Raman spectra taken of solution grown crystals as well as thin layers deposited by organic molecular beam deposition onto silicon substrates.

The Raman spectra of corresponding crystals show upwards shifts with respect to those of powders. This phenomenon was ascribed in literature [1,2] to the presence of water molecule in the crystal unit cell. In order to understand the vibrational properties of cytosine crystals several molecules with incorporated water molecules are considered in the calculations. [1] Nature, 408 (2000), 949-951. [2] Journal of Molecular Structure 349 (1995), 421-426.