In cases of problematic open-shell references, e.g., strongly
spin-contaminated doublet radicals, one may choose to use DFT orbitals, which
can yield significantly improved results.
Phys. Chem. Chem. Phys.
(2003), 5, pp. 2488. This can be achieved by first doing DFT calculation and then reading the orbitals and turning the SCF procedure off.
$molecule 0 3 C H 1 CH H 1 CH 2 HCH CH = 1.07 HCH = 111.0 $end $rem EXCHANGE b3lyp BASIS cc-pvdz $end @@@ $molecule read $end $rem BASIS cc-pvdz METHOD ccsd SCF_GUESS read MAX_SCF_CYCLES 0 N_FROZEN_CORE 1 $end