Determination of the resonance energy and width of the (2)B(2g) shape resonance of ethylene with the method of analytical continuation in the coupling constant.

Abstract

The method of analytical continuation in the coupling constant, which allows us to determine the energy and width of a shape resonance, has been applied to the study of the (2)B2g shape resonance of ethylene. The procedure was done in two steps. In the first step, we used commercially available quantum-chemistry programs to calculate the electronic energy of a neutral molecule and of a negative ion. In both calculations, the Hamiltonian was altered by the inclusion of an additional attractive potential that helps to keep the negative ion bound. In the second step, the energy difference between the neutral molecule and its negative ion was analytically continued by the use of the statistical Padé approximation.