• DOI:10.1038/ncomms2459
• Corpus ID: 5410050

Electronic signature of the instantaneous asymmetry in the first coordination shell of liquid water

@article{Khne2013ElectronicSO,
  title={Electronic signature of the instantaneous asymmetry in the first coordination shell of liquid water},
  author={Thomas D. K{\"u}hne and Rustam Z. Khaliullin},
  journal={Nature Communications},
  year={2013},
  volume={4}
}

• T. Kühne, R. Z. Khaliullin
• Published 19 January 2013
• Physics, Chemistry
• Nature Communications

Interpretation of the X-ray spectra of water as evidence for its asymmetric structure has challenged the conventional symmetric nearly tetrahedral model and initiated an intense debate about the order and symmetry of the hydrogen-bond network in water. Here we present new insights into the nature of local interactions in water obtained using a novel energy-decomposition method. Our simulations reveal that although a water molecule forms, on average, two strong donor and two strong acceptor bonds, there is a significant asymmetry in the energy of these contacts. We demonstrate that this asymmetry is a result of small instantaneous distortions of hydrogen bonds, which appear as fluctuations on a time scale of hundreds of femtoseconds around the average symmetric structure. Furthermore, we show that the distinct features of the X-ray absorption spectra originate from molecules with high instantaneous asymmetry. Our findings have important implications as they help reconcile the symmetric and asymmetric views on the structure of water. There are conflicting views about the symmetrical/asymmetrical nature of the hydrogen-bond network in water. This theoretical study reveals that water molecules in liquid form highly asymmetric hydrogen bonds and that this asymmetry relaxes rapidly towards an average symmetrical structure.