individual gauge for localized orbitals

https://doi.org/10.1351/goldbook.IT07055
A method of calculation of nuclear shieldings, in which localized molecular orbitals associated with inner shell, bonding orbitals, and lone pairs have unique origins for the calculation of @D01668@ and @P04404@ terms. With this method, satisfactory estimates of NMR chemical shifts for elements in the first and second rows can be achieved in ab initio calculations with basis sets of moderate size provided sufficiently accurate molecular geometries are used.
Source:
PAC, 1999, 71, 1919. (Glossary of terms used in theoretical organic chemistry) on page 1946 [Terms] [Paper]