RESUMO
In this work, we present the comparison study of guanine and cytosine crystals based on the hydrogen bond (HB) dynamics. The ab initio molecular dynamics gave us a base for detailed analysis. The analysis of the trajectories by power spectrum generation, as well as the fluctuation of the interaction energies, showed large differences between HB networks in the considered crystals. The charge flow is present in the guanine molecule which forms the flat surfaces in the crystals. In the cytosine zigzag structure, the charge flow is blocked. The interaction energy is significantly less stabilizing in the cytosine structure than in the guanine. Finally, the possible influence of charge transfer on the melting temperature has been discussed.
RESUMO
In this work we present the comparison study of Adenine and Thymine crystals based on the hydrogen bond dynamics. The ab initio molecular dynamics have been used as the base for the further studied interactions observed inside crystals. The generated power spectra, as well as the fluctuation of the interaction energies, showed large differences between hydrogen bond networks in the considered crystals. The analysis of intermolecular interactions have been done base on the reactivity descriptors as well frontiers orbitals along trajectories. The main results showed that in adenine crystals the intermolecular interactions have three directions and fluctuate, while in the thymine crystal have only two directions and are weak but stable. These results explain also on the difference between adenine and thymine melting temperature.