Multistep shell model description of spin-aligned neutron-proton pair   coupling: The formalism
  The multistep shell model was extended recently to incorporate both neutron and proton degrees of freedom and applied to study the structure of $N=Z$ systems with four, six and eight particles [arXiv:1108.0269]. In this work we give a brief introduction to the formalism thus developed. A more detailed explanation with applications will be updated later. 
Zhen-Xiang Xu, Chong Qi, Roberto J. Liotta, Ramon Wyss
nucl-th