| Title | A program library for computing pure spin-angular coefficients for one- and two-particle operators in non-relativistic atomic theory |
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| Authors | Gaigalas, Gediminas |
| DOI | 10.3390/atoms14040029 |
| Full Text |
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| Is Part of | Atoms.. Basel : MDPI. 2026, vol. 14, iss. 4, art. no. 29, p. [1-97].. eISSN 2218-2004 |
| Keywords [eng] | complex atom ; configuration interaction ; energy level ; LS-coupling ; matrix element ; quasi-spin ; Racah algebra ; recoupling coefficients ; reduced matrix element ; completely reduced matrix ; second quantization ; spin-angular integration ; tensorial operators ; theoretical methods |
| Abstract [eng] | A program library, libang77, for computing pure spin-angular coefficients for any one- and scalar two-particle operator is presented. The method is based on the combination of the second quantization and quasi-spin techniques with angular momentum theory and the method of irreducible tensorial sets. A non-relativistic approach is used, in which relativistic corrections may be included in the Breit–Pauli approximation. This program library, libang77, is integrated into the Atomic Structure Package ATSP2K [ATSP2K, C. Froese Fischer, G. Tachiev, G. Gaigalas, and M.R. Godefroid, Comput. Phys. Commun. (2007). DOI: 10.1016/j.cpc.2007.01.006], but it can be implemented in other program packages too. |
| Published | Basel : MDPI |
| Type | Journal article |
| Language | English |
| Publication date | 2026 |
| CC license |
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