The ChkBasis keyword requests that the basis set be read from the checkpoint file. It is useful in compound jobs involving general basis sets by allowing them to have only one copy of the basis set in the input stream. Note, however, that ChkBasis can be used to retrieve whatever basis set exists in a checkpoint file, regardless of how it was originally specified. ECPs specified in the basis set are also retrieved, as are the choices for pure vs. Cartesian functions.
By default, ChkBasis will also retrieve any density fitting basis in the checkpoint file. See the examples for other possibilities.
Of course, no basis set keyword should be specified with ChkBasis.
CheckBasis, CheckPointBasis, ReadBasis, and RdBasis are all synonyms for ChkBasis.
The following route section will retrieve the basis set and density fitting set (if any) from the checkpoint file and use them for the current job:
# B3LYP/ChkBasis
The following route section will retrieve only the basis set from the checkpoint file, and an automatically generated density fitting basis will be used:
# B3LYP/ChkBasis/Auto
The following route section will retrieve only the density fitting basis from the checkpoint file:
# B3LYP/6-31G(d)/ChkBasis
