Ice structures, patterns, and processes: A view across the ice-fields

We look ahead from the frontiers of research on ice dynamics in its broadest sense; on the structures of ice, the patterns or morphologies it may assume, and the physical and chemical processes in which it is involved. We highlight open questions in the various fields of ice research in nature; ranging from terrestrial and oceanic ice on Earth, to ice in the atmosphere, to ice on other solar system bodies and in interstellar space

Proton transfer and autoionization in HNO3·HCl· (H2O)n particles

The structure and spectroscopic properties of clusters of HNO 3·HCl·(H2O)n, with n = 1 to 6, have been calculated at the MP2/aug-cc-pVDZ level of theory. Altogether 22 different clusters have been found as stable structures, with minima in their potential energy surfaces. The clusters can be grouped in families with the same number of water molecules, and with close aggregation energies within each family. The addition of each new water molecule increments the aggregation energy of the clusters by a nearly constant value of 76.2 ± 0.1 Hartree. The proton transfer parameter and the coordination number of HNO3 and HCl in each cluster have been evaluated, and the wavenumber shifts for the X--H+ vibration from the corresponding mode in the isolated molecules have also been predicted. These values allow classification of the acidic species in the clusters into three types, characterized by the strength of the hydrogen bond and the degree of ionization. A correspondence is found between the coordination number of HNO3 and the magnitude of the X--H+ vibrational shift. © Royal Society of Chemistry 2011.TUBITAK (Project No: 107T044) and SDU (Project No:2211-D-10); Spanish Ministry of Science and Innovation, Projects FIS2007-61686 and FIS2010-16455, and Sabbatical Project PR2010-0012; Spanish Ministry of Science and Innovation, Project CTQ-2008-02578/ BQU and Consolider Ingenio Program 2010 CSD2009-0038.Peer Reviewe

Bonding Properties of HNO3.HOCL.(H2O)n Clusters

XXIV RNE-VIII CIE Espectroscopía, Logroño, 9-11 de julio (2014)Nitric acid and hypochlorous acid are species of atmospheric relevance [1,2]: ClONO2(g)+H2 O(s)¿ HOCl(g)+HNO3 (s) Also, HOCl and HCl are strongly coupled in the atmospheric chemistry: Cl2(g) + H2 O(l)¿ HOCl(l) + HCl Molecular clusters containing water and these acidic species are a subject of interest, especially in what concerns their bonding characteristics and spectroscopic properties. We have studied these clusters under several theoretical facets, which include energetics, proton transfer, atomic charges and IR spectra.RE and PGC acknowledge support from the Spanish Ministry of Science and Innovation, Projects FIS2010‐16455 and CTQ2008‐02578/BQU, respectivelyPeer Reviewe

Hydration of HNO3-HOCl clusters: Bonding properties

Molecular clusters of atmospheric relevance containing water and two acidic species, HNO3 and HOCl, are studied using several theoretical techniques, with especial emphasis on their bonding characteristics. Stable structures are found with a minimum in their potential energy surface for aggregates with three and four H2O molecules. In the most stable configurations the H atom of HNO3 is partly donated to the O atom of HOCl. A full proton transfer only takes place for some aggregates when four H2O molecules are present. Proton transfer parameters, electron density at the bond critical point, atomic charges and spectroscopic properties are studied for all these species, revealing direct relationships among several of these properties. The proton transfer parameter gives a straightforward indication of the degree of ionization of the aggregates, with negative or positive values for molecular or ionic (i.e. with fully ionized nitric acid) clusters, respectively. The calculated electron densities yield values typical of hydrogen bonded species. A linear correlation is found between proton transfer parameters and electron density values. Atomic charges are calculated using three different methods, namely Mulliken, Natural Bond Order, and Bader, with sometimes fairly large differences in the estimated values. The predicted spectra present large variations in wavenumber and intensity of the main bands, which could be used to identify specific aggregates among complex spectra. Finally, the effect of the strength of the chlorinated acidic species is evaluated by comparing the HOCl clusters studied here with similar aggregates containing HCl. The weaker acid favors a higher degree of proton sharing in HNO3. © 2014 Elsevier B.V.FMB and NU-A are appreciative of support for this project by TUBITAK (Project No: 107T044) and SDU (Project No:2211-D-10).The stay of NU-A in University Complutense has been supported by EU within the frame of the Erasmus Mundus ASC Master course (FPA 2008-0082). RE and PGC acknowledge support from the Spanish Ministry of Science and Innovation, Projects FIS2010-16455 and CTQ2008-02578/BQU, respectively.Peer Reviewe