By setting the $rem keyword BASIS = GEN, the user indicates that the basis set will be user defined. In that case, the $basis input section is used to specify the basis set. Similarly, if AUX_BASIS = GEN then the $aux_basis input section is used to specify the auxiliary basis set. AUX_BASIS_J, AUX_BASIS_K and AUX_BASIS_CORR can be specified same way in the $aux_basis_j, $aux_basis_k and $aux_basis_corr section. See Chapter 8 for details on how to input a user-defined basis set.