Dimensional perturbation theory: An efficient method for computing vibration-rotation spectra

Large-order perturbation theory in D-1/2, where D is the dimensionality of space, is shown to be an accurate and computationally efficient method for computing molecular vibration-rotation spectra. Results are presented for the ground vibrational state of CO2 with J as high as 80. The rate of convergence of the perturbation expansion increases with J and the computational cost scales only as JN(v)(5/3), where N-v is the number of vibrational basis functions. Therefore, this approach seems to be especially well suited for treating highly excited rotational states. (C) 1997 Elsevier Science B.V.