The GMCSC Method

As stated in the Introduction, the GMCSC method [1][2][25] is, in its roots, a multiconfiguration generalization of the well known spin-coupled approach [3]-[6]. 

The GMCSC wavefunction for a system of Ne electrons coupled to a resultant spin of S, with projection M (atomic units) along any given axis, can be written as [2]  

In the above equation, Nc is the fixed, but arbitrary, number of configurations included in the wavefunction, da the a-th configuration coefficient and 

Note x is used to denote collectively the space and spin coordinates of all electrons, while r denotes their space coordinates and a their spin coordinates. 

A stands for the antisymmetrizer in its usual idempotent form (hence the V (TV, ) in front of it in Eq. (2)), and Pa is a product of Ne orbitals (orbital string, or orbital configuration), 

---