Infrared vibrational spectra of CH3+ and its deuterated isotopologues

We report a theoretical study of the infrared (IR) vibrational spectra of CH3+ and its deuterated isotopologues. We also report exothermicities for reactions of these species with HD and D2. The calculations are performed using the two-layer Lanzcos algorithm with an exact full-dimensional molecular Hamiltonian, based on a slightly adjusted potential energy surface of Yu and Sears [H.-G. Yu and T. J. Sears, J. Chem. Phys. 117, 666 (2002)]. The transition strengths are evaluated within the traditional dipole approach. The full-dimensional dipole moment surfaces are calculated at CCSD(T)/cc-pVTZ level and fitted by integrity basis functions using a bond vector method. The results should be helpful for understanding the roles of CH3+ in the interstellar medium, especially in the coma of comet Halley.