Optical potential discrete variable representation method applied to the three-dimensional calculations of NeICl predissociation resonances

Abstract

Abstract The optical potential discrete variable representation (OP-DVR) method proposed to calculate resonances in the CO molecule [J. Chem. Phys. 101 (1994) 7580], is used in this paper to calculate three dimensional (3D) vibrational predissociation resonances of the Van der Waals complex NeICl on the B electronic surface (B, v = 2) for total angular momentum J = 0. The OP-DVR method is derived from Jolicard and Austin's work [Chem. Phys. Lett. 121 (1985) 106] who first used a complex absorbing potential (CAP) to calculate resonances in the context of the stabilization method. The OP-DVR method is based on the conjoint use of a CAP and the accurate and efficient discrete variable representation (DVR) method. The successive adiabatic reduction method of Bacic and Light [J. Chem. Phys. 85 (1986) 4594], holding the bending coordinate θ fixed, is used to reduce the dimension of the 3D Hamiltonian matrix. The CAP is added in the asymptotic region of the potential to impose the suitable resonance boundary conditions. The OP-DVR method requires the use of complex algebra and calculations of eigenvalues and eigenvectors of complex symmetric matrices. In this paper a systematic study of the convergence of all v = 2 resonances of the NeICl complex with respect to the parameters of the grid points (number of points and length of the grid) and the parameters of the CAP (position, range and strength) is performed. Resonances calculated with our method are compared to those obtained by Ryaboy et al. [J. Chem. Phys. 101 (1994) 5677], who used both the complex scaled coordinate discrete variable representation (CSC-DVR) method and the modified stabilization method proposed by Mandelshtam, Ravuri and Taylor [Phys. Rev. Lett. 70 (1993) 1932].