London atomic orbitals , nuclear

Lee, A. M., Handy, N. C., Colwell, S. M., 1995, The Density Functional Calculation of Nuclear Shielding Constants using London Atomic Orbitals , J. Chem. Phys., 103, 10095. 

K. Ruud, T. Helgaker, R. Kobayashi, P. Jorgensen, K. Bak, H. Jensen, Multiconfigurational self-consistent field calculations of nuclear shieldings using london atomic orbitals, J. Chem. Phys. 100 (1994) 8178. 

Lee AM, Handy NC, Colwell SM (1995) The density functional calculation of nuclear shielding constants using London atomic orbitals. J ChemPhys 103 10095-10109 Lippmaa,E, Magi M, Samoson A, Engelhard G, Grimmer,A-R (1980) Structural studies of silicates by solid-state high-resolution Si NMR. J Am Chem Soc 102 4889-4893 Lipscomb WN (1966) The chemical shift and other second-order magnetic and electric properties of small molecules. In Adv Mag Reson, Vol. 2, p 137-176... 

The reader will recall that in Chapter 2 we gave examples of H2 calculations in which the orbitals were restricted to one or the other of the atomic centers and in Chapter 3 the examples used orbitals that range over more than one nuclear center. The genealogies of these two general sorts of wave functions can be traced back to the original Heitler-London approach and the Coulson-Fisher[15] approach, respectively. For the purposes of discussion in this chapter we will say the former approach uses local orbitals and the latter, nonlocal orbitals. One of the principal differences between these approaches revolves around the occurrence of the so-called ionic structures in the local orbital approach. We will describe the two methods in some detail and then return to the question of ionic stmctures in Chapter 8. 

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