Solvent-separated anion pairs in concentrated solutions. — Hydrogen bonding to chloride ions in various aqueous environments has been discussed many times over the past more than 5 decades. Still, the possible role of such anion-to-water type hydrogen bonds (HB) in networks of HB-s has not been investigated in any detail. Here, computer models of concentrated aqueous LiCl solutions are considered and usual HB network characteristics, such as distributions of cluster sizes and of cyclic entities, are computed for the models by (1) taking and (2) not taking chloride ions into account. During the analysis of hydrogen bonded rings, a significant amount of ‘solvent separated anion pairs’ (see Fig.1) have been detected at high LiCl concentrations. It is demonstrated that including the halide anions into the network does make the interpretation of structural details significantly more meaningful than when considering water molecules only. Finally, simulated structures generated by ‘good’ and ‘bad’ potential sets have been compared on the basis of the tools developed here, and it is shown that the novel concept (1) is, indeed, helpful from this respect, too. 
Figure 1. Snapshot of a simulated particle configuration with a very high LiCl concentration of 19.55 mol/kg. A 5-membered ring is in the front, with 2 Cl- ions and 3 water molecules; the two anions are separated by a water molecule, i.e., the anions are `solvent-separated`.
Temperature-dependent structure of alcohol—water liquid mixtures. — Our group is in the midst of a long-term systematic investigation in this field; as a first step, experimental and simulated results have been published  for methanol-water mixtures. Experimentally, these mixtures have been investigated by high-energy synchrotron X-ray and neutron diffraction at low temperatures. It was thus possible to report the first complete sets of both X-ray and neutron weighted total scattering structure factors over the entire composition range (at 12 different methanol concentrations (xM) from 10 to 100 mol%) and at temperatures from ambient down to the freezing points of the mixtures. The new diffraction data may later be used as reference in future theoretical and simulation studies. Measured data were interpreted by molecular dynamics simulations, in which the all atom OPLS/AA force field model for methanol was combined with both the SPC/E and TIP4P/2005 water potentials. Both combinations provide at least semi-quantitative agreement with measured diffraction data. As a general trend, the average number of hydrogen bonds increases upon cooling. However, the number of hydrogen bonds between methanol molecules slightly decreases with lowering temperatures in the concentration range between ca. 30 and 60 mol % alcohol content. The same is valid for water-water hydrogen bonds above 70 mol % of methanol content, from room temperature down to 193 K.
Short range order and topology of Ge-Ga-Te glasses. — Due to their broad infrared transmission window glassy tellurides are extensively used in various fields of IR optics. The general strategy to find tellurides with excellent glass forming ability is to alloy the prototype Ge-Te system with a third component. Glasses with Ge-X-Te (X = Ga, As, Se, I, Ag, AgI) composition often possess a broad supercooled liquid region that makes it possible to shape bulk infrared lenses or draw fibers transmitting up to at least 18 μm. Structural background of glass forming of GexGaxTe100-2x (x = 7.5, 10, 12.5, 14.3) glasses was investigated by diffraction techniques and EXAFS . Models were obtained by fitting experimental datasets simultaneously in the framework of the reverse Monte Carlo simulation technique. It was shown that Ga and Ge atoms are mostly fourfold coordinated while NTe, the average coordination number of Te increases with Ga content (NTe = 2.35 ± 0.1 for x = 14.3). The majority of Ge/Ga atoms are linked to other Ge/Ga atoms via one or two common Te neighbors forming corner and edge sharing tetrahedra.
Figure 2. Part of the model of the Ge7.5Ga7.5Te85 glass obtained by RMC simulation. The Ge, Ga and Te atoms are represented by magenta, blue and grey balls, respectively. Two corner sharing tetrahedra are marked with orange, a short chain of Te atoms is highlighted by red
 Pethes, I.; Bakó, I.; Pusztai, L. Chloride ions as integral parts of hydrogen bonded networks in aqueous salt solutions: the appearance of solvent separated anion pairs. PHYSICAL CHEMISTRY CHEMICAL PHYSICS 22 : 19 pp. 11038-11044. , 7 p. (2020)
 Pethes, I.; Pusztai, L.; Ohara, K. ; Kohara, S. ; Darpentigny, J. ; Temleitner, L. Temperature-dependent structure of methanol-water mixtures on cooling: X-ray and neutron diffraction and molecular dynamics simulations. JOURNAL OF MOLECULAR LIQUIDS 314 Paper: 113664 , 10 p. (2020)
 Pethes, I. ; Piarristeguy, A. ; Pradel, A. ; Michalik, S. ; Nemausat, R. ; Darpentigny, J.; Jóvári, P. Short range order and topology of GexGaxTe100-2x glasses. JOURNAL OF ALLOYS AND COMPOUNDS 834 Paper: 155097 , 9 p. (2020)