Calculation of cross section for Li^- production in dissociative electron attachment to LiH molecule
Abstrakt
We present the description of the dissociative electron attachment to the LiH molecule within the discrete-state-in-continuum model [1]. Our attention has been primarily focused on the production of Li - ions occurring via the A2Σ + shape resonance mechanism.
The LiH molecule is interesting from the point of view of astrophysics since it participated in chemical processes in the early Universe [2]. From the theoretical viewpoint its description is challenging due to a large dipole moment and strong correlation of electronic and nuclear motions [3].
We describe the process in terms of the discrete state, which represents the A2Σ+ state of LiH , interacting with the e + LiH continuum. The model is based on potential energy curves of LiH and LiH - from MRCI calculations, together with eigenphase sums of e - + LiH scattering obtained by the R -matrix method.
Several models, which reproduce the ab-initio data very well, were constructed with a qualitatively different threshold behaviour of the decay width. The cross section of the Li - production is about four orders of magnitude larger than in the case of the H - production in the dissociative electron attachment to the H 2 molecule.
The mutual relative difference among the models is about 20 %. References [1] W.
Domcke, Phys. Rep. 208 , (1991), 97. [2] P.
C. Stancil, S.
Lepp, and A. Dalgarno, Astrophys.
J. 458 , (1996), 401. [3] F. X.
Gadéa and T. Leininger, Theor.
Chem. Acc. 116 , (2006), 56.