The Hermitian representation of the complex-rotation method and its application to the 1s2s2 2S resonance of He-

Abstract

The spectrum of the H operator, fundamental for the Hermitian representation of the complex-coordinate method, is proven to be symmetric with respect to zero. This property makes the effective application of H eigenproblems possible, instead of H2 eigenproblems. The Hermitian representation complex-coordinate method modified in this way is applied, with a superposition of correlated configurations as a trial function, to the He- 1s2s2 2S resonance and gives the position at 19.367 eV above the He ground state and a width of 8.6 meV.