LOW-LYING LEVELS IN CERTAIN ACTINIDE ATOMS
Calculating the ordering and properties of low-lying levels in configurations of the type 5f/sup n/6d falls into (a) the choice of a coupling scheme to define the basic eigenfunctions; (b) the evaluation of the matrix elements of the spinorbit interaction and of the Coulomb interaction in the form of linear combinations of certain radial integrals; (c) the estimation of the radial integrals; (d) the diagonalization of the energy matrices. With regard to (a), the J coupling scheme is considered to be the most appropriate; this implies that the Coulomb interaction between the core, comprising the equivalent f electrons, and the d electron (to whose levels the respective symbols J and j refer) is weak compared with the interactions within the two systems. Part (b) is carried out by applying the tensor operator and group theoretical methods of Racah. For (c), values of the integrals F/sub k/ (5f,6d) and G/sub k/(5f,6d) are estimated by assuming that they maintain the ratios one to another as they do in Th/sub III/, and that their variation along the actinide series parallels the variation of G/sup 3/(5f,7s). The last parameter is known for Thi/sub III/ and analyses of U/sub II/, Pu/sub II/, and Am/sub II/ show that it decreases, advancing along the actdnide series. This decline is interpreted as being due to the collapse of the 5f shell, and the internal nature of the 5f electrons allows general statements to be made about the spin-orbit coupling constants. Additional information on the parameters is provided by an analysis of the properties of the four lowest levels of Cm Part (d) is accomplished for the lowest levels of f/sup 2/d, f/sup 3/d, f/sup 4/d, f/sup 8/d, and f/sup 10/d by neglecting all off-diagonal elements; for U/sub I/ fad, where extensive spectroscopic information is available, the interaction of the levels deriving from the J/sub j/ coupling of 4/sub I 9/2/ to /sup 2/D:, with those de riving from the coupling of /sup 4/I/sub 121/2 to /sub 2/D/sub 5/2/. is included. Where experimental data are available, agreement with the theory is good. (auth)
- Research Organization:
- Univ. of California, Berkeley, CA (United States)
- NSA Number:
- NSA-16-009326
- OSTI ID:
- 4813952
- Report Number(s):
- UCRL-9779; 0031-899X
- Journal Information:
- Physical Review (U.S.) Superseded in part by Phys. Rev. A, Phys. Rev. B: Solid State, Phys. Rev. C, and Phys. Rev. D, Vol. Vol: 125; Other Information: UCRL-9779. Orig. Receipt Date: 31-DEC-62
- Country of Publication:
- United States
- Language:
- English
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