We estimate the line spacing between vibrational levels for the antisymmetric stretching in [ClDCl] to elucidate the origin of the oscillating structure on the translational energy distribution of the terminal D atom released by the photodissociation of (DCl)(2). The vibrational analysis with the symmetrically combined Morse potential model is performed for linear hydrogen-bonding [ClDCl] and the dependence of change in vibrational levels on the Cl-Cl distance is examined. It is found that the calculated assignment and observed spacing show good correspondence for RClCl = 3.65 or 3.70 Angstrom, and it is therefore strongly suggested that the oscillation of dissociated D translational energy reflects the antisymmetric stretching vibration in the [ClDCl] counterpart.