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Pressure effects in the properties of simple monohydric alcohols. Lessons from molecular dynamics simulations of united atom type UAM-EW model

M. Aguilar, L. Pusztai, O. Pizio

Abstract

We explore the pressure dependence of a set of properties of simple monohydric alcohols, namely of methanol, ethanol and 1-propanol, by using isobaric-isothermal molecular dynamics computer simulations. A recently proposed united atom, non-polarizable force field for each of alcohols [V. García-Melgarejo et al., J. Mol. Liq., 323, 114576 (2021)] is applied. Accuracy of the force field is evaluated by comparing the simulation results and available experimental data from the literature. Specifically, the density of alcohols upon increasing pressure, the isothermal compressibility, the static dielectric constant and self-diffusion coefficient are investigated starting from 1 bar up to 3 kbar. Evolution of the microscopic structure under pressure is discussed in terms of the pair distribution functions and some coordination numbers. Conclusions of the present modelling and necessary developments to consider in future work are commented on.

Pressure effects in the properties of simple monohydric alcohols. Lessons from molecular dynamics simulations of united atom type UAM-EW model

Abstract

We explore the pressure dependence of a set of properties of simple monohydric alcohols, namely of methanol, ethanol and 1-propanol, by using isobaric-isothermal molecular dynamics computer simulations. A recently proposed united atom, non-polarizable force field for each of alcohols [V. García-Melgarejo et al., J. Mol. Liq., 323, 114576 (2021)] is applied. Accuracy of the force field is evaluated by comparing the simulation results and available experimental data from the literature. Specifically, the density of alcohols upon increasing pressure, the isothermal compressibility, the static dielectric constant and self-diffusion coefficient are investigated starting from 1 bar up to 3 kbar. Evolution of the microscopic structure under pressure is discussed in terms of the pair distribution functions and some coordination numbers. Conclusions of the present modelling and necessary developments to consider in future work are commented on.
Paper Structure (8 sections, 4 equations, 11 figures, 2 tables)

This paper contains 8 sections, 4 equations, 11 figures, 2 tables.

Table of Contents

  1. Introduction
  2. Models and simulation details
  3. Results and discussion
  4. Density and isothermal compressibility
  5. Dielectric constant
  6. Self-diffusion coefficients
  7. Microscopic structure
  8. Summary and conclusions

Figures (11)

  • Figure 1: (Colour online) Panels a, b and c: Methanol, ethanol and propanol density on pressure at 298.15 K, respectively. The simulation results are for the UAM-EW united atom models. The experimental data are from kubota-metkubota-met2nist (panel a), kubota-ethabdul (panel b), and munozlifi (panel c).
  • Figure 2: (Colour online) Pressure dependence of the isothermal compressibility for MeOH (panel a), EtOH (panel b), and PrOH (panel c). The experimental data are from taravillo for MeOH; from pecar (solid triangles) and kubota-eth (hollow triangles) for EtOH, respectively; and from lifi for PrOH.
  • Figure 3: (Colour online) Panels a, b, c and d: Illustration of the calculations of dielectric constant of methanol, ethanol and 1-propanol at different pressures (indicated in the figure) at 298.15 K. The simulation results are for UAM-EW united atom model. The experimental data (dashed lines in all panels) are from moriyoshi.
  • Figure 4: (Colour online) Static dielectric constant of alcohols on pressure at 298.15 K. The simulation results are for the UAM-EW united atom model. The experimental data (solid lines with triangles) are from moriyoshi.
  • Figure 5: (Colour online) Self-diffusion coefficient of alcohols on pressure at 298.15 K. The simulation results (circles and dotted lines) are for the UAM-EW united atom model at 298.15 K. The experimental data (dashed lines with triangles) are from Hurle et al. hurle (methanol and ethanol at 298.15 K). The experimental data for PrOH are for a C3H7DO sample at 296.5 K from Shaker-Goafar et al. karger.
  • ...and 6 more figures