Theoretical X-ray absorption spectra of water and ice

One of the remarkable instances of progress in soft-X-ray spectroscopy recently is the successful high-resolution measurement of O-K edge absorption spectra of liquid water and ice, which have some disordered hydrogen-bonds. Professor R. Car (Princeton University) and his colleagues have recently reported their theoretical studies into the quantum dynamics of the nuclei and inhomogeneous screening effects. They found that the inclusion of quantum disorder is essential to bring the calculated spectra in close agreement with the experiment. In particular, the intensity of the pre-edge feature, a spectral signature of broken and distorted hydrogen bonds, is accurately reproduced, in water and hexagonal ice, only when quantum nuclei are considered. The effect of the inhomogeneous screening is less important but non-negligible, particularly in ice. For more information, see the paper, "Roles of quantum nuclei and inhomogeneous screening in the x-ray absorption spectra of water and ice", L. Kong et al., Phys. Rev. B86, 134203 (2012).