basis set

https://doi.org/10.1351/goldbook.BT06999
A set of basis functions employed for the representation of molecular orbitals. One may distinguish the minimal basis set (includes one @[email protected] for each SCF occupied atomic orbital with distinct principal and @[email protected] quantum numbers); split @[email protected] basis set (includes two or more sizes of @[email protected] for each @[email protected] orbital); double @[email protected] (DZ) basis set (a split @[email protected] basis set that includes exactly twice as many functions as the minimal basis set); extended basis set (the set larger than the double @[email protected] basis set); polarized basis set (incorporates basis functions of higher angular quantum number beyond what is required by the atom in its electronic @[email protected]; allows orbitals to change not only a size, but also a shape); basis set with diffuse functions and others.
Source:
PAC, 1999, 71, 1919. (Glossary of terms used in theoretical organic chemistry) on page 1925 [Terms] [Paper]