  The absorption spectrum of the title compound in the spectral range of the
Hydrogen-bonded OH-stretching vibration has been investigated using a
five-dimensional gas phase model as well as a QM/MM classical molecular
dynamics simulation in solution. The gas phase model predicts a Fermi-resonance
between the OH-stretching fundamental and the first OH-bending overtone
transition with considerable oscillator strength redistribution. The anharmonic
coupling to a low-frequency vibration of the Hydrogen bond leading to a
vibrational progression is studied within a diabatic potential energy curve
model. The condensed phase simulation of the dipole-dipole correlation function
results in a broad band in the 3000 \cm region in good agreement with
experimental data. Further, weaker absorption features around 2600 \cm have
been identified as being due to motion of the Hydrogen within the Hydrogen
bond.
