The original implementation is documented fairly thoroughly in Georg Schreckenbach's Ph.D. thesis (University of Calgary, 1996), which is available at http://www.scm.com/Doc/publist.html, as well as in the following papers:
Georg Schreckenbach and Tom Ziegler,
[5] J. Phys. Chem. 1995, 99, 606. (NMR all-electron formulation)
[6] Int. J. Quantum Chem. 1996, 60, 753. (frozen core approximation)
[7] Int. J. Quantum Chem. 1997, 61, 899. (scalar relativistic method
[8] J. Phys. Chem. A 1997, 101, 3388. (ESR g-tensor)
S. Patchkovskii et al.
[9] S. Patchkovskii, T. Ziegler, J. Phys. Chem. 2001, A105, 5490. (High-spin EPR g-tensor)
[17] S. Patchkovskii, R.S. Strong, C.J. Pickard, and S. Un, J. Chem. Phys. 2005, 122, 214101.
(spin-other orbit term g-tensor)
There are also various application papers published. These papers illustrate some of the concepts and functionality that is described here.
