Density functional theory study of the hydrogen bonding interaction of the dimers of formylhalide

The hydrogen bonding of the dimers of formylhalide has been completely investigated in the present study using density functional theory (DFT), HF and second-order Moller-Plesset Perturbation (MP2) methods with the 6-311++g(d,p) basis set. Four reasonable geometries on the potential energy hypersurface of the dimers of formylhalide system are considered with the global minimum being a cyclic double-hydrogen bonded structure. The optimized geometric parameters and interaction energies for various isomers are estimated. The infrared spectrum frequencies, IR intensities and the vibrational frequency shifts are reported.