Computational and vibrational spectroscopy study of the microclusters of C2 symmetry urea molecule in the 1A electronic ground state

A series of microclusters containing up to eigtht C2 symmetry urea molecules was studied at the B3LYP density functional theory level. The equilibrium structures of each aggregate and the respective theoretical infrared spectra were determined from B3LYP/6-311++G** calculations. Relative stability considerations and binding energy of each species were obtained from MP2/6-311++G**//B3LYP/6-311++G** single point calculations, including basis set superposition error (BSSE) and zero-point energy (ZPE) corrections. Further single point energy calculations at the MP2/6-311++G(3df,3pd)//B3LYP/6-311++G** level were made for all dimers and trimers. The theoretical study of these aggregates was integrated with FT-IR spectroscopy measurements in low temperature argon matrixes.