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# AO_BASIS

> 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

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