II. Temperature trends in the properties of simple monohydric alcohols. Molecular dynamics simulations of united atom UAMI-EW model

Abstract

We explore the dependence of a wide set of properties of monohydric alcohols on temperature by using the isobaric-isothermal molecular dynamics computer simulations. Namely, methanol (MeOH), ethanol (EtOH) and 1-propanol (PrOH) alcohols are studied. The recently proposed united atom, non-polarizable force field for each of alcohols [V. García-Melgarejo et al., J. Mol. Liq., 2021, 323, 114576] is applied for this purpose. Accuracy of the force field is discussed comparing predictions from simulations and experimental data for density, dielectric constant, surface tension, and self-diffusion coefficient. Supplementary insights concerning applicability of the model are obtained by exploration of the composition dependence of various properties for MeOH-PrOH mixtures. Peculiarities of mixing of species in this system are elucidated in terms of density, excess mixing volume and excess mixing enthalpy. Static dielectric constant of the mixture and the corresponding excess are obtained. Perspectives of modelling are commented finally.

Figures (10)

• Figure 1: (Colour online) Panel a: methanol density on temperature at pressure 1 bar. The experimental data (black short-dashed line and solid circles) are from NIST Chemistry Webbook nist and from reference valtz (blue hollow triangles). Panel b: ethanol density on temperature. The experimental data are from: Sun et al. sun (black circles) and reference valtz (blue hollow triangles). Panel c: experimental data from moreau (black circles), valtz (blue hollow triangles). Our simulation data of UAM-EW model are given by red dashed line with solid squares in all panels.
• Figure 2: (Colour online) Panel a: dielectric constant of methanol on temperature. The experimental data in panel a are from reference kay (black solid cicles), dannhauser (hollow circles), davidson (blue triangles). The simulation results (red squares in panels a, c and d) are for UAMI-EW united atom model. Panel b: illustration of the calculations of dielectric constant of methanol. Panel c: experimental data are from reference dannhauser (black solid circles), kay (shaded circles), moriyoshi (blue triangles), respectively. Panel d: experimental data are from references moriyoshi (black circles) and dannhauser (triangles), respectively.
• Figure 3: (Colour online) Panel a: surface tension of methanol on temperature. The experimental data in panel a are from referencestrey (circles), souckova (triangles) and vazquez (diamonds), respectively. Panels b and c: the same as in panel a, but for EtOH and PrOH, respectively. Experimental data are from reference strey (circles --- in panels b and c) and from vazquez (triangles) in panel b. The simulation results in all panels are for UAMI-EW united atom model (squares).
• Figure 4: (Colour online) Panel a: self-diffusion coefficient of methanol on temperature. Experimental data are from hurlekarger (solid circles), and karger (hollow circles). Panel b: self diffusion coefficient of ethanol on temperature (experimental data --- pratt, karger, solid and hollow circles, respectively). Panel c: self diffusion coefficient of PrOH on temperature (experimental data --- prattshaker, circles and triangles, respectively).
• Figure 5: (Colour online) Panel a: a comparison of simulation data (red squares) for the composition dependence of density for MeOH--PrOH mixture with experimental data (circles) from kumagai. Panel b: density of MeOH--PrOH mixture on composition from simulations, and experimental data borun, nomenclature of symbols as in panel a, green triangles reproduced from figure 1a of reference madhurima --- simulation of OPLS/AA model.