Fig. 1. A schematic representation of the RNEMD method.

Fig. 2. RNEMD shear viscosity evolution over time for 1,4-butanediol at 25 MPa and 373 K. (a) The “x” directional velocity profile in “y” direction. (b) Evolution of viscosity as function of time. Four different swap rates are included; black, red, green, and blue lines represent rates resulting from one swap every 20, 40, 50, and 80 outer timesteps, respectively. (For interpretation of the references to color in this figure legend, the reader is referred to the web version of the article.)

Fig. 3. The shear viscosities as a function of shear rate for all five systems. Black circles, red triangles, green diamonds, and blue squares are used to represent 0.1, 25, 100, and 250 MPa, respectively. (For interpretation of the references to color in this figure legend, the reader is referred to the web version of the article.)

Fig. 4. Superposition of the data sets at 0.1, 25, and 250 MPa onto the data set at 100 MPa. The Carreau fit is given by the dashed lines for respective sets. Black, red, green, blue, and orange symbols and lines are used to represent 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 2-methyl-1,3-propanediol, and 1,2,4-butanetriol, respectively. Open symbols are experimental Newtonian viscosities at 100 MPa. (For interpretation of the references to color in this figure legend, the reader is referred to the web version of the article.)

Fig. 5. Comparison of experimental (open symbols and lines) and simulated (filled symbols) viscosities as a function of pressure at 373 K. Colors as in Fig. 4. (For interpretation of the references to color in this figure legend, the reader is referred to the web version of the article.)

Fig. 6. Intermolecular oxygen–oxygen (upper) and oxygen–hydroxyl hydrogen (lower) radial distribution functions and their corresponding number integrals (inset) at p=0.1 MPa. Colors as in Fig. 4. (For interpretation of the references to color in this figure legend, the reader is referred to the web version of the article.)

Fig. 7. Pressure dependence of the intermolecular oxygen–oxygen (black 0.1 MPa, green 250 MPa) and oxygen–hydroxyl hydrogen (red 0.1 MPa, blue 250 MPa) radial distribution functions. Shown from left to right are 1,2-butanediol, 1,3-butanediol, and 1,4-butanediol. (For interpretation of the references to color in this figure legend, the reader is referred to the web version of the article.)

Fig. 8. Intramolecular oxygen–oxygen (upper) and oxygen–hydroxyl hydrogen radial distribution functions at p=0.1 MPa. Colors as in Fig. 4 except that 1–2, 1–4, and 2–4 pairs for 1,2,4-butanetriol are shown as solid, dotted and dashed lines, respectively. (For interpretation of the references to color in this figure legend, the reader is referred to the web version of the article.)

Fig. 9. Distribution of interaction energies between intermolecular CH_x–O–H groups at 0.1 MPa (upper) and 250 MPa (lower). Colors as in Fig. 4. (For interpretation of the references to color in this figure legend, the reader is referred to the web version of the article.)

Fig. 10. Probability a molecule is in a hydrogen bonded aggregate as function of aggregate size at 0.1 MPa (upper) and 250 MPa (lower). Colors as in Fig. 4. (For interpretation of the references to color in this figure legend, the reader is referred to the web version of the article.)

Fig. 11. Principal moments of inertia at 0.1 MPa (left) and 250 MPa (right). Shown from top to bottom are 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 2-methyl-1,3-butanediol, and 1,2,4-butanetriol.

Fig. 12. Vapor–liquid coexistence curves. Saturated liquid and vapor densities and critical points for the TraPPE-UA force field are shown as filled and open circles, respectively, while experimental results [54] and [55] are given as solid lines for the saturated liquid densities, as horizontal dashed line for the critical temperature (when the critical density is not known), and as stars for the critical point. Colors as in Fig. 4. (For interpretation of the references to color in this figure legend, the reader is referred to the web version of the article.)

Fig. 13. Clausius–Clapeyron plots for polyhydric alcohols. The experimental data [54] and [55] and predictions by the TraPPE-UA force field are shown as solid lines and filled symbols, respectively. Colors as in Fig. 4. (For interpretation of the references to color in this figure legend, the reader is referred to the web version of the article.)

Fig. 14. Heats of vaporization vs. temperature computed for the TraPPE-UA force field and from experiment. [54] and [61] Line and symbol styles as in Fig. 12. (For interpretation of the references to color in this figure legend, the reader is referred to the web version of the article.)

Shear viscosities of the systems used to validate the method

Subscripts indicate the statistical uncertainties in the final digit.

Non-bonded, torsional, bond bending and bond length parameters for the TraPPE-UA force field and bond stretching parameters from the AMBER force field

Liquid densities (g/mL) for the TraPPE-UA force field computed from isobaric–isothermal MC simulations at 373 K

Subscripts indicate the statistical uncertainties in the final digit. For comparison, the experimental values at 373 K and 0.1 MPa for 1,2-butanediol, 1,3-butanediol, and 1,4-butanediol are 0.942, 0.949, and 0.967 g/mL, respectively [60].

Viscosities (cP) for the TraPPE-UA force field computed from molecular dynamics simulations at 373 K and comparison to available experimental data [1]

Subscripts indicate the statistical uncertainties in the final digit(s).

Parameters for the Carreau fit as given in Eq. (12)

The estimates of η₀ are in cP, λ are in ps, while parameter p is dimensionless. Subscripts indicate the statistical uncertainties in the final digit(s).

Average numbers of hydrogen bonds per molecule computed from isobaric–isothermal MC simulations at 373 K

Subscripts indicate the statistical uncertainties in the final digit.

Ratios of the principal moments of inertia computed from isobaric–isothermal MC simulations at 373 K

Subscripts indicate uncertainties in the final digit.

Comparison of normal boiling points and critical properties measured experimentally and predicted from GEMC simulations for the TraPPE-UA force field

Subscripts indicate the statistical uncertainties in the final digits.

Numerical results of GEMC simulations for the TraPPE-UA force field: saturated liquid density, saturated vapor density, saturated vapor pressure, heat of vaporization, entropy of vaporization, and number of intermolecular hydrogen bonds per molecule in the liquid phase

Temperatures, orthobaric densities, saturated vapor pressures, enthalpies of vaporization, and entropies of vaporization are given in units of K, g/mL, MPa, kJ/mol, and J/mol K, respectively. Subscripts indicate the statistical uncertainties in the final digit.