Specifies the AO basis used in the calculation. One can either specify a basis known to CFOUR or via BASIS=SPECIAL (=0) requests an arbitrary basis (see non-standard basis-set input). However, the latter must be available in the supplied GENBAS file. As standard basis sets, currently the following are available. Psi4 Interface: Recommended to use instead BASIS for larger basis set selection and greater flexibility. When BASIS used, CFOUR_SPHERICAL is set appropriately.
- Type: string
- Default: SPECIAL
