CCSD(T) inversion spectrum for H3O+

Mass independent bidimensional potential energy surfaces (including the inversion and the symmetric stretch) for H3O+ have been calculated using the CCSD(T) ab initio method with augmented triple and quadruple zeta basis sets. All surfaces have been fitted using high order Chebyshev polynomials, and the vibrational inversion spectra have been calculated using similar methods we recently introduced in the study of ammonia. A good agreement with the experimental inversion values: a mean absolute error of 11.9 cm(-1) with the triple zeta basis set, and of 5.6 cm(-1) with the quadruple zeta basis set was obtained. (C) 2002 Elsevier Science B.V. All rights reserved.