In order to use a user-defined basis set the BASIS *$rem* must be
set to GENERAL or GEN.

When using a non-standard basis set which incorporates $d$ or higher angular
momentum basis functions, the *$rem* variable PURECART needs to be
initiated. This *$rem* variable indicates to the Q-Chem program how to handle
the angular form of the basis functions. As indicated above, each integer
represents an angular momentum type which can be defined as either pure (1) or
Cartesian (2). For example, 111 would specify all $g$, $f$ and $d$ basis
functions as being in the pure form. 121 would indicate $g$- and $d$-
functions are pure and $f$-functions Cartesian.

PURECART

INTEGER

TYPE:

Controls the use of pure (spherical harmonic) or Cartesian angular forms

DEFAULT:

2111
Cartesian $h$-functions and pure $g,f,d$ functions

OPTIONS:

$hgfd$
Use 1 for pure and 2 for Cartesian.

RECOMMENDATION:

This is pre-defined for all standard basis sets

In standard basis sets all functions are pure, except for the $d$ functions
in $n$-21G–type bases (*e.g.*, 3-21G) and $n$-31G bases (*e.g.*, 6-31G,
6-31G*,6-31+G*, $\mathrm{\dots}$). In particular, the 6-311G series uses pure
functions for both $d$ and $f$.