Panel (a): one-site potentials obtained with (solid) and without (dashed) virial constraint at , , and difference between potentials with and without virial constraint at (GPa): 0.0 (solid/filled circles) and 0.5 (dashed/filled circles). Panel (b): difference between two-site MS-CG potentials for NM with and without virial constraint at (GPa): 0.0 (no symbol) and 0.5 (filled circles). Shown potentials are NO–NO (solid), CH–NO (dashed), and CH–CH (dotted-dashed).
One-site MS-CG/0.0 potentials of NM obtained with the virial and compressibility constraints (solid) and with only virial constraint (dashed). Dotted line outlines NM-NM RDF in arbitrary units.
Panel (a): one-site potentials of liquid NM at and different densities corresponding to pressures (GPa): −0.1040 (filled circles), −0.0304 (filled squares), 0.0 (solid), 0.0641 (empty squares), 0.5 (empty circles), 1.0 (empty triangles), 2.0 (stars), and 5.0 (crosses). Panel (b): two-site nonbonded potentials at pressures (GPa): 0.0 (no symbols) and 0.5 (empty circles). Shown potentials are NO–NO (solid), CH–NO (dashed), and CH–CH (dotted-dashed). Dotted lines outline NM-NM RDF in panel (a) and NO-NO RDF in panel (b) in arbitrary units with vertical lines marking outer edge of the respective first coordination shell.
Two-site bonded potentials [panel (a)] and forces [panel (b)] at different pressures (GPa): 0.0 (solid/filled circles), 0.5 (dashed/filled circles), 2.0 (solid), and 5.0 (dashed).
Comparison of coarse-grain RDFs from MS-CG (thin/black) and reference atomistic (thick/color) simulations at different pressures for one-site [panel (a)] and two-site [panel (b)] models of NM.
Comparison of one-site MS-CG potential at , (thick dashed line) with the potentials obtained at and (GPa): −0.0304 (filled squares), 0.0 (solid), 0.0641 (empty squares), and 0.5 (empty circles). Dotted lines outline NM-NM RDF in arbitrary units.
VDOS from atomistic (dashed) and MS-CG/0.0 (solid) simulations for liquid at [panel (a)] and crystal at [panel (b)] at . For atomistic simulation the VDOS shown for all-atom (red), one-site (blue), and two-site (green) trajectories. The same color scheme used for VDOS from one- and two-site MS-CG/0.0 models. In panel (b) the region corresponding to the intramolecular mode of the two-site MS-CG model is shown with a high resolution.
Hugoniot curve for NM from atomistic (solid/empty squares), one-site (dashed/cross) and two-site (solid/filled squares) MS-CG/0.0 models, and two-site density dependent MS-CG-D (empty triangles) model. Circles are experiment from Ref. 84 (filled circles) and Ref. 85 (empty circles).
Properties of bulk liquid NM at and different pressures from atomistic, one- and two-site , and MS-CG-D models. Properties from the two-site MS-CG/0.0 model are given in last column. The properties listed here are density , the average nonbonded configuration energy per particle (kJ/mol), and isothermal compressibility . For two numbers are shown, which are from and MS-CG-D simulations. For and one number is shown as these properties are same for the and MS-CG-D models at the reference . For and , standard deviations are shown in parentheses.
Lattice parameters , , and , unit cell volume and corresponding density , nonbonded energy per molecule at different temperatures from atomistic model and two-site MS-CG/0.0 models matched to liquid NM at and , and MS-CG/–1.040 and MS-CG/2.0 models at . The simulation data were obtained from simulations with anisotropic barostat.
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