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Coarse-grained models for the solvents dimethyl sulfoxide, chloroform, and methanol
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10.1063/1.3681140
/content/aip/journal/jcp/136/5/10.1063/1.3681140
http://aip.metastore.ingenta.com/content/aip/journal/jcp/136/5/10.1063/1.3681140

Figures

Image of FIG. 1.
FIG. 1.

Schematic representation of a CG bead and the associated CG force-field parameters. m denotes the mass of a particle; the definition of the remaining parameters is given in Eqs. (1)–(4). The values of the parameters in each CG solvent model are given in Table I.

Image of FIG. 2.
FIG. 2.

Distributions of the atom-positional root-mean-square deviation (rmsd) between all atoms of a cluster and its COG, averaged over the total number of clusters N cl and over 10 configurations of the unrestrained FG MD simulations, for clusters comprising two (solid), three (dashed), or four (dotted) FG molecules for DMSO, CHCl3, and MeOH as labeled.

Image of FIG. 3.
FIG. 3.

Intercluster non-covalent potential energy (black) and its components (red) and (green), averaged over all pairs of clusters (α, β) and over a 5 ns MD simulation at 298 K, plotted as a function of the intercluster distance r αβ between the COG of clusters of size N mol = 2 (DMSO and CHCl3) or N mol = 4 (MeOH).

Image of FIG. 4.
FIG. 4.

Properties of mixtures of CG DMSO and H2O as a function of the mole fraction of DMSO xDMSO. (a) density ρ, (b) dielectric permittivity ε(0), (c) excess volume of mixing ΔV mix, and (d) excess enthalpy of mixing ΔU mix: (filled circles, solid line) experimental data, (open circles, solid line) values calculated from CG simulations using the standard GROMOS mixing rules and (open triangles, dashed line) values calculated from CG simulations using optimized mixing rules. The experimental values of ρ, ΔV mix, and ΔU mix are from Cowie and Toporowski23 and those of ε(0) are from Kaatze et al. 24

Image of FIG. 5.
FIG. 5.

Properties of mixtures of CG MeOH and H2O as a function of the mole fraction of MeOH xMeOH. (a) density ρ, (b) dielectric permittivity ε(0), (c) excess volume of mixing ΔV mix, and (d) excess enthalpy of mixing ΔU mix: (filled circles, solid line) experimental data, (open circles, solid line) values calculated from CG simulations using the standard GROMOS mixing rules and (open triangles, dashed line) values calculated from CG simulations using optimized mixing rules. The experimental values of ρ and ΔV mix are from Mikhail et al.,25 values of ε(0) are from Kanse et al. 26 and those of ΔU mix are from Beggerow.27

Image of FIG. 6.
FIG. 6.

Properties of mixtures of CG MeOH and DMSO as a function of the mole fraction of MeOH xMeOH. (a) density ρ, (b) dielectric permittivity ε(0), (c) excess volume of mixing ΔV mix, and (d) excess enthalpy of mixing ΔU mix: (filled circles or squares, solid line) experimental data, (open circles, solid line) values calculated from CG simulations using the standard GROMOS mixing rules and (open triangles, dashed line) values calculated from CG simulations using optimized mixing rules. The experimental values of ρ, ΔV mix, and ε(0) are from Romanowski et al. 28 and the two sets of ΔU mix are from (circles) Quitzsch et al. 29 and (squares) Drinkard and Kivelson,31 as published in the Handbook of Heats of Mixing.32

Image of FIG. 7.
FIG. 7.

Radial distribution functions g(r) of mixtures of CG DMSO and H2O, where r represents the distance between the central particle of pairs of CG beads of the same or different type as labeled, for (black) xDMSO = 0.000, (red) xDMSO = 0.188, (green) xDMSO = 0.349, (blue) xDMSO = 0.478, (violet) xDMSO = 0.814, and (cyan) xDMSO = 1.000.

Image of FIG. 8.
FIG. 8.

Radial distribution functions g(r) of mixtures of CG MeOH and H2O, where r represents the distance between the central particle of pairs of CG beads of the same or different type as labeled, for (black) xMeOH = 0.0, (red) xMeOH = 0.1, (green) xMeOH = 0.2, (blue) xMeOH = 0.3, (yellow) xMeOH = 0.4, (violet) xMeOH = 0.5, (cyan) xMeOH = 0.6, (magenta) xMeOH = 0.7, (orange) xMeOH = 0.8, (indigo) xMeOH = 0.9, and (turquoise) xMeOH = 1.0.

Image of FIG. 9.
FIG. 9.

Radial distribution functions g(r) of mixtures of CG MeOH and DMSO, where r represents the distance between the central particle of pairs of CG beads of the same or different type as labeled, for (black) xMeOH = 0.0, (red) xMeOH = 0.2, (green) xMeOH = 0.4, (blue) xMeOH = 0.5, (violet) xMeOH = 0.6, (cyan) xMeOH = 0.8, and (magenta) xMeOH = 1.0.

Image of FIG. 10.
FIG. 10.

Excess free energy and free energy of solvation ΔG solv of a NEOP bead for mixtures of CG DMSO:H2O, MeOH:H2O, or MeOH:DMSO as a function of the mole fraction of DMSO (xDMSO) or MeOH (xMeOH) as labeled.

Tables

Generic image for table
Table I.

Optimized parameters for the CG models of DMSO, CHCl3, MeOH, and NEOP. N mol is the number of FG molecules represented by each CG bead, m denotes the mass of the particles, and the other quantities are defined in Eqs. (1)–(4). All models were parameterized under NpT conditions at 298 K and 1 atm, using an intra-bead relative dielectric permittivity εcs of 2.5 and a non-covalent interaction cut-off radius R c of 2.0 nm.

Generic image for table
Table II.

Comparison of the density ρ, intercluster or interbead potential energy V pot and its Lennard-Jones and Coulomb reaction field components V LJ and V CRF, average dipole moment , relative static dielectric permittivity ε(0), surface tension γ, and self-diffusion coefficient D measured experimentally and calculated from simulations using FG and CG models of each solvent. All experiments and MD simulations were conducted at 298 K and 1 atm unless specified otherwise. Note that the values given in the first line of the FG data are for individual FG molecules, whereas the second line, labeled FGcl, gives values for clusters of FG molecules, meant for comparison to the CG value.

Generic image for table
Table III.

Comparison of the isothermal compressibility κ T determined experimentally with those calculated from FG and CG simulations of each solvent. The density ρ and pressure p of the simulations from which κ T was calculated by interpolation are given where known; a “−” indicates that the value of this property was not reported.

Generic image for table
Table IV.

Comparison of the thermal expansion coefficient α and the heat capacity C p determined experimentally with those calculated from FG and CG simulations of each solvent. The temperature T and density ρ of the simulations from which α and C p were calculated by interpolation are given where known; a “−” indicates that the value of this property was not reported.

Generic image for table
Table V.

Excess free energies and NEOP solvation free energies ΔG solv calculated from the simulations of pure CG liquids and measured experimentally. All values are in kJ mol−1.

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/content/aip/journal/jcp/136/5/10.1063/1.3681140
2012-02-03
2014-04-23
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752b84549af89a08dbdd7fdb8b9568b5 journal.articlezxybnytfddd
Scitation: Coarse-grained models for the solvents dimethyl sulfoxide, chloroform, and methanol
http://aip.metastore.ingenta.com/content/aip/journal/jcp/136/5/10.1063/1.3681140
10.1063/1.3681140
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