How to use the customized basis set |Gen and GenECP|

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A set of standard basis sets is stored internally in Gaussian; these basis sets may be specified by including the appropriate keyword within the route section for the calculation. The Gen keyword allows a user-specified basis set to be used in a Gaussian calculation. It is used in place of a basis set keyword or a density-fitting basis set keyword. In this case, the basis set description must be provided as input (in a separate basis set input section).

Gen may be analogously used to specify an alternate density fitting basis set (see the examples).

The GenECP variation may be used to read in both basis functions and ECPs; it is equivalent to Gen Pseudo=Read. It is designed for use in ONIOM calculations in which you want to use a general basis set with ECPs within one ONIOM layer.

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