Widening of the hydrogen bonded OH-streching bands due to the wagging and OO-stretching modes in H2O·H2O

We have calculated band profiles of the hydrogen bonded OH-stretching bands in H2O · H2O, using a local mode Hamiltonian which includes the low-energy acceptor wagging and the high energy OH-stretching motion. We use the method previously developed for coupling of OH- and OO-stretching modes. Our current results confirms that low frequency modes will lead to wider OH-stretching bands. The spread of intensity and shape of the profile from coupling to the acceptor wagging mode is different to that found from coupling to the OO-stretching mode. Combination of both results yields an OH-stretching band profile, which is around 250 cm−1 wide in the third OH-stretching overtone.