Feshbach resonances in electron-molecule scattering by the complex multiconfiguration SCF and configuration interaction procedures: The 1Σg+ autoionizing states of H2

Satoshi Yabushita, C. William McCurdy

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Abstract

The complex resonance energies (positions and widths) and wave functions for the lowest 1Σg+ doubly excited autoionizing states of H2 are directly computed by using the multiconfiguration self-consistent field (MCSCF) method and the configuration interaction (CI) method within the context of the complex basis function technique. These autoionizing states are Feshbach resonances (as opposed to shape resonances), and single-configuration self-consistent field calculations provide no information about the lifetimes of such states. All of these methods rely on the existence of a complex variational principle for complex resonance energies. It is shown that by using a small orbital space the MCSCF method can give essentially the same complex energies as the full CI method. Numerical results are in good agreement with previous theoretical results, especially with the optical potential calculation employing a diffuse basis set by Schneider and Collins [Phys. Rev. A 28, 166 (1983)], indicating that poor agreement with previous complex coordinate results by Moiseyev and Corcoran [Phys. Rev. A 20, 814 (1979)] is attributable to their small basis set. A detailed study of basis set and correlation effects on the complex energies is also presented.

Original languageEnglish
Pages (from-to)3547-3559
Number of pages13
JournalThe Journal of Chemical Physics
Volume83
Issue number7
Publication statusPublished - 1985
Externally publishedYes

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configuration interaction
self consistent fields
Scattering
Molecules
Electrons
scattering
molecules
electrons
interactions
energy
variational principles
Wave functions
Excited states
wave functions
orbitals
life (durability)
configurations
excitation

ASJC Scopus subject areas

  • Atomic and Molecular Physics, and Optics

Cite this

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title = "Feshbach resonances in electron-molecule scattering by the complex multiconfiguration SCF and configuration interaction procedures: The 1Σg+ autoionizing states of H2",
abstract = "The complex resonance energies (positions and widths) and wave functions for the lowest 1Σg+ doubly excited autoionizing states of H2 are directly computed by using the multiconfiguration self-consistent field (MCSCF) method and the configuration interaction (CI) method within the context of the complex basis function technique. These autoionizing states are Feshbach resonances (as opposed to shape resonances), and single-configuration self-consistent field calculations provide no information about the lifetimes of such states. All of these methods rely on the existence of a complex variational principle for complex resonance energies. It is shown that by using a small orbital space the MCSCF method can give essentially the same complex energies as the full CI method. Numerical results are in good agreement with previous theoretical results, especially with the optical potential calculation employing a diffuse basis set by Schneider and Collins [Phys. Rev. A 28, 166 (1983)], indicating that poor agreement with previous complex coordinate results by Moiseyev and Corcoran [Phys. Rev. A 20, 814 (1979)] is attributable to their small basis set. A detailed study of basis set and correlation effects on the complex energies is also presented.",
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AU - Yabushita, Satoshi

AU - McCurdy, C. William

PY - 1985

Y1 - 1985

N2 - The complex resonance energies (positions and widths) and wave functions for the lowest 1Σg+ doubly excited autoionizing states of H2 are directly computed by using the multiconfiguration self-consistent field (MCSCF) method and the configuration interaction (CI) method within the context of the complex basis function technique. These autoionizing states are Feshbach resonances (as opposed to shape resonances), and single-configuration self-consistent field calculations provide no information about the lifetimes of such states. All of these methods rely on the existence of a complex variational principle for complex resonance energies. It is shown that by using a small orbital space the MCSCF method can give essentially the same complex energies as the full CI method. Numerical results are in good agreement with previous theoretical results, especially with the optical potential calculation employing a diffuse basis set by Schneider and Collins [Phys. Rev. A 28, 166 (1983)], indicating that poor agreement with previous complex coordinate results by Moiseyev and Corcoran [Phys. Rev. A 20, 814 (1979)] is attributable to their small basis set. A detailed study of basis set and correlation effects on the complex energies is also presented.

AB - The complex resonance energies (positions and widths) and wave functions for the lowest 1Σg+ doubly excited autoionizing states of H2 are directly computed by using the multiconfiguration self-consistent field (MCSCF) method and the configuration interaction (CI) method within the context of the complex basis function technique. These autoionizing states are Feshbach resonances (as opposed to shape resonances), and single-configuration self-consistent field calculations provide no information about the lifetimes of such states. All of these methods rely on the existence of a complex variational principle for complex resonance energies. It is shown that by using a small orbital space the MCSCF method can give essentially the same complex energies as the full CI method. Numerical results are in good agreement with previous theoretical results, especially with the optical potential calculation employing a diffuse basis set by Schneider and Collins [Phys. Rev. A 28, 166 (1983)], indicating that poor agreement with previous complex coordinate results by Moiseyev and Corcoran [Phys. Rev. A 20, 814 (1979)] is attributable to their small basis set. A detailed study of basis set and correlation effects on the complex energies is also presented.

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