Compare vibrational frequencies in CCCBDB for Cu2 (Copper dimer)
CISD/3-21G*Frequency in cm-1
See section XIII.C.3 List or set vibrational scaling factors to change the scale factors used here.
See section III.B.3.c Calculate a vibrational scaling factor for a set of molecules to determine the least squares best scaling factor.
See section III.B.3.b List of vibrational scaling factors and their uncertainties for information on where the above scaling factor is from.