Range Of Liquid States Research Articles

Machine learning models for phase transition and decomposition temperature of ionic liquids

The working temperature range of Ionic Liquids (IL) is determined by their liquid state range, where the IL’s melting point/glass transition and decomposition temperatures define the lower and upper limits of the range, respectively. Computational prediction of the structure of new ILs with required properties, e.g. which can exist in a liquid state at room temperature and are stable up to high temperatures, is a much less time-consuming and less expensive approach than stepwise synthesis and experimental examination of all presupposed ILs. Therefore, in the present work the quantitative structure–property relationship (QSPR) models were developed to predict the glass transition temperature (Tg), melting point (Tm), and decomposition temperatures (Td) of ILs. We showed that a use of component validation protocol provided a better agreement of statistical parameters for the training and test sets. The performance of various modeling algorithms and descriptor sets was discussed and compared and advantages of descriptor-less as well as multi-task modeling were shown. An explanation of the models using statistical analysis of functional groups and Molecular Matched Pairs were provided for the mixtures for the first time. The experimental data and models, which are the first publicly available models for prediction of transition and decomposition temperatures of ILs, are publicly available online at http://ochem.eu/article/140250.

Equilibrium molecular dynamics simulation of shear viscosity of two-dimensional complex (dusty) plasmas

Shear viscosity is examined throughout the entire range of strongly coupled states of two-dimensional complex (dusty) plasma liquids (CDPLs). We have employed equilibrium molecular dynamics (EMD) simulation to compute the shear viscosity coefficients of CDPLs. In the strongly coupled liquid region, the values of valid viscosity coefficient can be estimated only in order of magnitude. The variations in the valid viscosity coefficients with screening strength (κ) and Coulomb coupling strengths (Γ) are observed. A systematic dependence of shear viscosity on κ is observed for an intermediate and higher Γ. The investigations showed that the position of the minimum viscosity coefficient shifts towards higher Γ as κ increases. The computational results for the entire range of liquid states of the strongly coupled dusty plasma obtained using the shear autocorrelation functions are in good agreement with the available simulation results and experimental data. It is shown that new simulations extended the range of plasma states (Γ, κ) used in our earlier simulation results for the existence of a finite minimum possible viscosity coefficient and it is also dependent on plasma states.

The temperature dependence of mercury saturated vapor pressure over the whole range of its liquid state

The Boltzmann distribution with normalization with respect to the boiling point was used to calculate the temperature dependence of vapor pressure, which included the temperature and heat of boiling only. A refined equation of mercury vaporizability with mutually consistent characteristics such as vapor pressure and the temperature and heat of boiling was obtained. The equation correctly described this dependence over the whole liquid state range, including the critical point.

Diffusion in vibrating-molecule liquids

The self-diffusion coefficient for a homonuclear diatomic liquid of vibrating molecules, resembling nitrogen, but with a wide range of vibration frequencies, is determined by computer simulation for a wide range of liquid states. The values are found to differ little from those for the corresponding rigid-molecule liquid and are remarkably insensitive to the vibration even for very-low-frequency and large-amplitude vibrations. We do not believe that explicit inclusion of molecular flexibility is likely to materially affect the gross dynamical properties of a molecular liquid.