8.4.2 Job Control

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.

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 $f$.