Analytic continuation and Green function calculations
L J Gray; T Kaplan; L J Gray; Div. of Eng. Phys. & Math., Oak Ridge Nat. Lab., TN, USA; T Kaplan; Div. of Eng. Phys. & Math., Oak Ridge Nat. Lab., TN, USA
Журнал:
Journal of Physics A: Mathematical and General
Дата:
1986-06-21
Аннотация:
Hass, Velicky and Ehrenreich (1984) have shown that Green function values can be obtained appreciably faster by performing the calculation at complex energies with large imaginary parts, and then returning to real energies by an analytic continuation algorithm. However, analytic continuation is numerically unstable and thus an error analysis is essential if one is to have confidence in the results of the continuation. Error estimates are obtained for the power series method of Hass et al. and for a method based upon Cauchy's theorem introduced herein. These estimates can be used to select appropriate values for the parameters of the continuation algorithms.
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