A FINITE BASIS-DISCRETE VARIABLE REPRESENTATION CALCULATION OF VIBRATIONAL LEVELS OF PLANAR ACETYLENE

A methodology for the calculation of high energy vibrational eigenstates of S0 acetylene is described. Acetylene is modeled as a 5D planar molecule. The discrete variable representation (DVR) is employed for radial coordinates with a finite basis representation (FBR) for the angular coordinates. Symmetry adaptation of the primitive basis (dimension 2.7 X 10(6) coupled with a two level diagonalization/truncation scheme maintains relatively small basis sets (< 2500 functions) in all diagonalizations. Eigenvalues up to nearly 3700 cm-1 above the ground state are reported.