Calculation of the hydrogen binding energies of complexes between formamide and adenine-thymine pair

The hydrogen bonding of complexes formed between formamide and adenine-thymine base pair has been completely investigated in the present study. In order to gain deeper insight into structure, charge distribution, and energies of complexes, we have investigated them using density functional theory at 6-311++G(d, p), 6-31G, 6-31+G(d), and 6-31++G(d, p) level. Seven stable cyclic structures (ATF1-ATF7) being involved in the interaction has been found on the potential energy surface. In addition, for further correction of interaction energies between adenine-thymine and formamide, the basis set superposition error associated with the hydrogen bond energy has been computed via the counterpoise method using the individual bases as fragments. The infrared spectrum frequencies, IR intensities and the vibrational frequency shifts are reported.