Calculations of the discrete Cl 1s and 2p excitation spectra of HCl are performed employing accurate ab-initio . . Configuration Interaction CI and Density Functional DF approaches. The core excited spectra above edge are described with a new DF method based on a one-centre approximation. The highly correlated quasi-degenerate perturbation scheme gives results in excellent accord with experimental data and allows a definite assignment of the Rydberg excited states below edge. The simpler 1h–1p CI scheme shows some deficiencies essentially attributed to the use of inadequate orbitals, although it appears adequate for a qualitative description of the spectra. The DF approach provides dependable results for the lower-energy states of the discrete spectra while some limitations affect the present description of the higher Rydberg states. Good agreement with experimental data is obtained for the calculated cross-section profiles relative to the Cl 1s and 2p photoionization. Also the theoretical asymmetry parameter profiles are analysed. q1998 Elsevier Science B.V. All rights reserved.
Theoretical study of the Cl 1s and 2p near edge photoabsorption spectra of HCl by accurate ab-initio CI and density functional approaches
FRONZONI, GIOVANNA;STENER, MAURO;DECLEVA, PIETRO;DE ALTI, GIANCARLO
1998-01-01
Abstract
Calculations of the discrete Cl 1s and 2p excitation spectra of HCl are performed employing accurate ab-initio . . Configuration Interaction CI and Density Functional DF approaches. The core excited spectra above edge are described with a new DF method based on a one-centre approximation. The highly correlated quasi-degenerate perturbation scheme gives results in excellent accord with experimental data and allows a definite assignment of the Rydberg excited states below edge. The simpler 1h–1p CI scheme shows some deficiencies essentially attributed to the use of inadequate orbitals, although it appears adequate for a qualitative description of the spectra. The DF approach provides dependable results for the lower-energy states of the discrete spectra while some limitations affect the present description of the higher Rydberg states. Good agreement with experimental data is obtained for the calculated cross-section profiles relative to the Cl 1s and 2p photoionization. Also the theoretical asymmetry parameter profiles are analysed. q1998 Elsevier Science B.V. All rights reserved.Pubblicazioni consigliate
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