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.