Stabilizing potentials in bound state analytic continuation methods for electronic resonances in polyatomic molecules.
The computation of Siegert energies by analytic continuation of bound state energies has recently been applied to shape resonances in polyatomic molecules by several authors. We critically evaluate a recently proposed analytic continuation method based on low order (type III) Padé approximants as well as an analytic continuation method based on high order (type II) Padé approximants. We compare three classes of stabilizing potentials: Coulomb potentials, Gaussian potentials, and attenuated Coulomb potentials. These methods are applied to a model potential where the correct answer is known exactly and to the Πg2 shape resonance of N2-which has been studied extensively by other methods. Both the choice of stabilizing potential and method of analytic continuation prove to be important to the accuracy of the results. We conclude that an attenuated Coulomb potential is the most effective of the three for bound state analytic continuation methods. With the proper potential, such methods show promise for algorithmic determination of the positions and widths of molecular shape resonances.
Department of Chemistry, University of California, Berkeley, California 94720, USA.
Alec F
AF
White
Department of Chemistry, University of California, Berkeley, California 94720, USA.
Martin
M
Head-Gordon
Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA.
C William
0000000308659195
CW
McCurdy