Using Density Functional Theory To Study Neutral and Ionized Stacked Thymine Dimers.
Stacking interactions in thymine dimers are studied with density functional theory. According to our calculations, six dimers of comparable stability can be prepared at low temperature, but dimerization is impossible at room temperature due to the large entropy contribution that accompanies it. Analysis of vibrational anharmonic coupling terms shows that each of the dimers exhibits distinct vibrational dynamics. Properties of electron density in the intermolecular region are used to analyze neutral stacked species and their ionized forms. Bond paths and critical points in the intermolecular region are identified, but a simple relationship between binding energy and total electron density in the intermolecular critical points could not be found due to an uneven electron distribution in the binding region. The reduced density gradient was confirmed to be a useful tool for analysis of weak stacking interactions. Those interactions also affect vertical and adiabatic ionization energies, which are computed to be slightly lower for the dimers compared to the monomer.
Faculty of Physical Chemistry, University of Belgrade , Studentski trg 12-16, 11 158 Belgrade, Serbia.
Đura
Đ
Nakarada
Faculty of Physical Chemistry, University of Belgrade , Studentski trg 12-16, 11 158 Belgrade, Serbia.
Mihajlo
M
Etinski
Faculty of Physical Chemistry, University of Belgrade , Studentski trg 12-16, 11 158 Belgrade, Serbia.
Milena
M
Petković
D019281:Dimerization; D004583:Electrons; D008956:Models, Chemical; D015394:Molecular Structure; D011740:Pyrimidine Dimers; D013696:Temperature; D013941:Thymine / Q000737:chemistry*; D014732:Vibration
D011740:Pyrimidine Dimers; D013941:Thymine