The algorithm to use for the 
terms If AO_BASIS is NONE, the MO-basis integrals will be used; if AO_BASIS is DISK, the AO-basis integrals stored on disk will be used; if AO_BASIS is DIRECT, the AO-basis integrals will be computed on the fly as necessary. NB: The DIRECT option is not fully implemented and should only be used by experts. Default is NONE. Note: The developers recommend use of this keyword only as a last resort because it significantly slows the calculation. The current algorithms for handling the MO-basis four-virtual-index integrals have been significantly improved and are preferable to the AO-based approach.
- Type: string
- Possible Values: NONE, DISK, DIRECT
- Default: NONE
