Potential energy surface and lower bound states of HCCH-Cl~-

摘要

Lower lying rovibrational energy levels of the acetylene-Cl~- anion complex are calculated using an ab initio potential energy surface (PES) computed at MP2/aug-cc-pVTZ level. The PES is characteirzed by a deep minimum in the linear cofniguration (D_e=3760 cm(~-1), R_e=3.97 A) and a purely repulsive intraction for a T-shaped configuration. Rovibrational calculations are performed on PEss that are adiablatically correctd for the influence of the local mode vibration of the intermediate proton (hydrogen-bonded C-H stretch mode). The adiabatic correction leads to an enhanced intermolecular interaction with a deepening of the potential well and shortening of the equilbrium intrmolecular separation. These effects becomes more pronounced as additional quanta are added to the hydrogen-bonded v_(CH) stretch mode. Band energies and rotational constants are calculated for states likely to be observable in spetroscopic searches. The predicted complexation-induced frequency shfit for the acetylene v_3 vibration is -446 cm~(-1).