Global potential energy surfaces for the CO2 and CS2 molecules

Global potential energy surfaces for the ground electronic states of the CO 2 and CS2 molecules are determined. We use the many-body single-value surfa ces previously constructed by Murrell and Guo (J. Chem. Sec. Faraday Trans. 2 (1987) 83, 683) and refine their parameters by the non-linear least-squa res method in order to reproduce the observed vibrational frequencies of ea ch molecule. The fits are made by computing variationally the vibrational f requencies using sets of optimal generalized internal coordinates. The qual ity of the potentials is checked by computing vibrational frequencies of is otopic species and highly excited vibrational energies nor included in the fits. (C) 1999 Elsevier science B.V. All rights reserved.