Don't allow the reference determinant to be updated in a CCMC simulation.
Don't allow the reference determinant to be updated in a CCMC simulation.

One really, really shouldn't change the reference determinant in
a truncated method, as doing so alters the Hilbert space!  Therefore, do
not allow it to happen in CCMC.

hande-qmc/hande,hande-qmc/hande,hande-qmc/hande,hande-qmc/hande,ruthfranklin/hande,hande-qmc/hande