2004/05/15 by G. Gaigalas
Physics and Astronomy · #physics.atom-ph
published as Lithuanian Journal of Physics 39 (1999) 79-105
arxiv created 2004/05/15 · arxiv updated 2009/12/01
A review of methods for finding general expressions for matrix elements (non-diagonal with respect to configurations included) of any one- and two-particle operator for an arbitrary number of shells in an atomic configuration is given. These methods are compared in various aspects, and the advantages or shortcomings of each particular method are discussed. Efficient method to find the abovementioned quantities in LS coupling is presented, based on the use of symmetry properties of operators and matrix elements in three spaces (orbital, spin and quasispin), second quantization in coupled tensorial form, graphical technique and Wick's theorem. This allows to efficiently account for correlation effects practically for any atom and ion of periodical table.