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Articles you may be interested inCalculation of the structure, potential energy surface, vibrational dynamics, and electric dipole properties for the Xe:HI van der Waals complexThe effect of weak interactions on the ring puckering potential in the coumaran-argon van der Waals complex: Experimental and ab initio analysis of the intermolecular and low-frequency intramolecular vibrationsThe mid-infrared (4000-400 cm Ϫ1 ) and far-infrared (300-10 cm Ϫ1 ) spectra of C 2 H 4 /HCl mixtures, dissolved in liquefied argon ͑93-125 K͒ and in liquefied nitrogen ͑80-118 K͒ are discussed. In all spectra, experimental evidence was found for the existence of 1:1 and 1:2 Van der Waals complexes. Using spectra recorded at different temperatures, the complexation enthalpy ⌬H°f or the 1:1 complex was determined to be Ϫ8.7(2) kJ mol Ϫ1 in liquid argon and Ϫ6.4(4) kJ mol Ϫ1 in liquid nitrogen, while for the 1:2 complex a ⌬H°of Ϫ18.3(6) kJ mol Ϫ1 was found. For all species studied, the vibrational frequencies were obtained from ab initio calculations at the MP2/6Ϫ311ϩG** level. Using the SCRF/SCIPCM scheme to correct for the solvent influences, and using statistical thermodynamics to account for the zero-point vibrational and thermal contributions, approximate values for the dissociation energy were calculated from the complexation enthalpies. The resulting values, Ϫ12.7(5) kJ mol Ϫ1 for the 1:1 complex and Ϫ26.9(2) kJ mol Ϫ1 for the 1:2 complex are compared with the ab initio values. The transition dipole moment of the 2 ethene mode induced in the 1:1 complex is determined to be 0.13 D Å Ϫ1 . A multipole analysis shows that the main contribution is due to the quadrupole moment of the HCl moiety, closely followed by that due to the dipole moment, with much smaller contributions due to higher multipoles. In the 1:1 complex, the HCl stretching intensity is enhanced by a factor of 7.7 in comparison with the monomer. This increase is interpreted in the equilibrium charge-charge flux model using ab initio atomic polar tensors.