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Ab initio molecular treatment for single and double electron capture in the He2+ + He (1s2) collision
Erratum
467
Chemical Physics 149 ( 199 I) 333-339 North-Holland
Ab initio molecular treatment for single and double electron capture in the He 2+ + He ( 1s2) collision M.C. Bacchus-Mont&one1 Luboratoire de Spectrom&n’eIonique et Mok?culaire(associt!au CNRS No. 171), UniversithLyon I. Btitiment 205.43 Boulevard du 1I Novembre 1918.69622 Vikurbanne Cedex, France
and M. Druetta Laboratoire de Traitement du Signal et Instrumentation (UA 842). UniversitPJean Monnet, 23 rue du Docteur M&Ion, 42023 St-Etienne Cedex 2, France Received 28 March 1990; in final form 6 September 1990
Adiabatic potential energy curves for ten ‘Z and six ‘II states of the Hd+ system have been calculated by means of all electron ab initio calculations including configuration interaction. AUthe non-zero radial and rotational coupling matrix elements between these ‘Z and ‘II states have been evaluated using CI wavefunctions. Values for the partial cross sections of single and double electron capture for the collisional process He*+ + He ( I s2)have been determined within a semiclassical formalism in the 20 keV energy range.
1. Intrudoction
The interpretation of electron capture processes in the collision of multiply charged ion species with a He target has been widely investigated experimentally as well as theoretically. One of the fundamental reactions in this field is the He’+ + He( 1s2) collision for which a great amount of experimental data is available [ l-5 1. From an experimental point of view, this system is indeed one of the most common ones and could be proposed as a benchmark for the crosssection calibration in WV spectroscopy experiments. Theoretical studies using the time-dependent Hat-tree-Fock approximation [ 61, a molecular-orbital expansion method [ 731 or recent coupledchannel A0 calculations [9] are in overall good agreement with experiment but they do not display the partial cross sections on the 2s and 2p levels of He+ in the collision process He2+ +He( ls2) + He+ (21) + He+ ( 1s ) and only the investigation of ref. [ 91 provides an evaluation of the double capture cross section in the collision process He2+ +He( 1s’) -+ 0301-0104/91/$03.50
He( Is, 21) +H 2+. The knowledge of these quantities would be useful for a fair comparison with experimental data. Besides, we have recently developed a full ab initid treatment for the study of the reactions of a multicharged ion on a He target in which the involved potential energy curves and radial and rotational coupling matrix elements are calculated by means of an ab initio configuration interaction method. These molecular quantities are then used in a semiclassical collisional treatment to provide partial cross se0 tions. The results already obtained using this approach for the two isoelectronic systems NS+(ls2)+He(1s2) [lO,ll] and 06+(1s2)+ He( ls2) [ 12-141 were seen to be in satisfactory agreement with experiment. Nevertheless to the best of our knowledge there exist no previous molecular calculations on the NHeS+ ion and only one molecular calculation [ 15 ] has been previously performed on the 0He6+ system so that no direct test of accuracy of the molecular part of our approach has been possible up to now. Present calculations have been
8 1991- Elsevier Science Publishers B.V. (North-Holland)
467
Chemical Physics 149 ( 199 I) 333-339 North-Holland
Ab initio molecular treatment for single and double electron capture in the He 2+ + He ( 1s2) collision M.C. Bacchus-Mont&one1 Luboratoire de Spectrom&n’eIonique et Mok?culaire(associt!au CNRS No. 171), UniversithLyon I. Btitiment 205.43 Boulevard du 1I Novembre 1918.69622 Vikurbanne Cedex, France
and M. Druetta Laboratoire de Traitement du Signal et Instrumentation (UA 842). UniversitPJean Monnet, 23 rue du Docteur M&Ion, 42023 St-Etienne Cedex 2, France Received 28 March 1990; in final form 6 September 1990
Adiabatic potential energy curves for ten ‘Z and six ‘II states of the Hd+ system have been calculated by means of all electron ab initio calculations including configuration interaction. AUthe non-zero radial and rotational coupling matrix elements between these ‘Z and ‘II states have been evaluated using CI wavefunctions. Values for the partial cross sections of single and double electron capture for the collisional process He*+ + He ( I s2)have been determined within a semiclassical formalism in the 20 keV energy range.
1. Intrudoction
The interpretation of electron capture processes in the collision of multiply charged ion species with a He target has been widely investigated experimentally as well as theoretically. One of the fundamental reactions in this field is the He’+ + He( 1s2) collision for which a great amount of experimental data is available [ l-5 1. From an experimental point of view, this system is indeed one of the most common ones and could be proposed as a benchmark for the crosssection calibration in WV spectroscopy experiments. Theoretical studies using the time-dependent Hat-tree-Fock approximation [ 61, a molecular-orbital expansion method [ 731 or recent coupledchannel A0 calculations [9] are in overall good agreement with experiment but they do not display the partial cross sections on the 2s and 2p levels of He+ in the collision process He2+ +He( ls2) + He+ (21) + He+ ( 1s ) and only the investigation of ref. [ 91 provides an evaluation of the double capture cross section in the collision process He2+ +He( 1s’) -+ 0301-0104/91/$03.50
He( Is, 21) +H 2+. The knowledge of these quantities would be useful for a fair comparison with experimental data. Besides, we have recently developed a full ab initid treatment for the study of the reactions of a multicharged ion on a He target in which the involved potential energy curves and radial and rotational coupling matrix elements are calculated by means of an ab initio configuration interaction method. These molecular quantities are then used in a semiclassical collisional treatment to provide partial cross se0 tions. The results already obtained using this approach for the two isoelectronic systems NS+(ls2)+He(1s2) [lO,ll] and 06+(1s2)+ He( ls2) [ 12-141 were seen to be in satisfactory agreement with experiment. Nevertheless to the best of our knowledge there exist no previous molecular calculations on the NHeS+ ion and only one molecular calculation [ 15 ] has been previously performed on the 0He6+ system so that no direct test of accuracy of the molecular part of our approach has been possible up to now. Present calculations have been
8 1991- Elsevier Science Publishers B.V. (North-Holland)