Publikace ÚTF

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 2B2g 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.