In the close coupling (CC) approximation the total wave function of the electron-ion system is represented as

where

is the target ion wave function in a specific state S_i L_i,

is the wave function for the free electron, and

are short range correlation functions for the bound (e + ion) system. Accurate CC calculations of atomic processes require, first of all, a good representation of the target ion. For complex ions an accurate representation must include a large number of correlation configurations. However, in order for the computations to be computationally tractable, the configuration expansion must be carefully and economically chosen.

The CC expansion for this calculation includes 31 LS terms of the target ion Fe V. The atomic structure code SUPERSTRUCTURE (Eissner etal. 1974; Eissner 1991) was used to compute eigenfunctions for the 31 states of the Fe V target ion dominated by

, and

. Table 1 (click here) presents the complete list of configurations included in the target, as well as a comparison between the calculated target term energies and the observed energies, averaged over the fine structure, taken from Sugar & Corliss (1985). The agreement between the energies is very good; in all but six cases the agreement with the experimental values is within

2%. The overall agreement is better than 4%. Another indicator of the accuracy of the target representation is the good agreement between the length and the velocity oscillator strengths (f-values), which for the present case is typically about 10% (for a complicated atomic system such as Fe IV it is to difficult to achieve higher accuracy for LS f-values).

	Level				Level
1		0.000000	0.00000	17		2.12336	2.161109
2		0.227038	0.232252	18		2.33251	2.355847
3		0.223059	0.259441	19		2.35148	2.386004
4		0.237769	0.261593	20		2.34905	2.419861
5		0.267818	0.309157	21		2.36577	2.391652
6		0.327553	0.379240	22		2.36838	2.397309
7		0.561290	0.618696	23		2.40378	2.440669
8		0.560546	0.618706	24		2.42943	2.469158
9		1.70206	1.695583	25		2.49342	2.534489
10		1.78024	1.782194	26		2.51746	2.556067
11		1.86264	1.874768	27		2.50752	2.551853
12		1.89927	1.910388	28		2.52243	2.558687
13		1.93610	1.963195	29		2.54016	2.585237
14		1.94802	1.975859	30		2.54951	2.597140
15		1.96486	1.984966	31		2.60523	2.623293
16		1.96974	1.985141