In 2004, the polarizability volume reported was modified by the use of additive corrections.

In `STATIC`, 37 or 38 SCF calculations are involved. The polarizability
involves 36 calculations, one for each electric field. The fields are +X, -X,
+2X, -2X, +Y, -Y, +2Y, -2Y, +X+Y, -X+Y, -X-Y, +X-Y, +2X+2Y, -2X+2Y, -2X-2Y,
+2X-2Y, +Z, -Z, +2Z, -2Z, +X+Z, -X+Z, -X-Z, +X-Z, +2X+2Z, -2X+2Z, -2X-2Z,
+2X-2Z, +Y+Z, -Y+Z, -Y-Z, +Y-Z, +2Y+2Z, -2Y+2Z, -2Y-2Z, and +2Y-2Z.
These are used in the construction of a three by three secular matrix, which
is then diagonalized, giving the orthogonal polarizabilities.

See also `POLAR`