Fig 1.
(a) Mass fluxes in the vicinity of vapor–liquid interface; (b) classification of molecules with vapor and liquid boundaries.
Fig 2.
(a) Calculation system in the present MD study; (b) density, temperature, and velocity profiles in system.
Fig 3.
Schematic of method to obtain molecular variables.
Reaching position zreach was defined as the minimum value of that the molecule had reached; staying time tstay was defined as the time that the molecule had stayed in the region on the liquid-phase side of the vapor boundary; ξin and ξout were molecular velocities along the z-direction when the molecule passed through the vapor boundary toward the liquid phase and vapor phase, respectively.
Fig 4.
Relationship between zreach and tstay of molecules in −3.0 < zreach < 3.0.
(a) Dataset representing relationship between zreach and tstay of molecules; (b) dataset in zreach– coordinate plane. Bins with dc × dc are set to calculate the values of the bivariate histogram. (c) Bivariate histogram of data points in zreach–
coordinate plane.
Fig 5.
(a) Dataset classified into two clusters. Blue dots represent the cluster of reflection molecules, and orange dots represent the cluster of condensation/evaporation molecules. Inset shows that the two clusters are divided by a dotted line at approximately zreach = −1.0. (b) Percentages of excluded molecules from each cluster in the case where the liquid boundary was set at .
Fig 6.
(a) Data points in −2.0 ≤ zreach ≤ 0.0 and 0 ps ≤ tstay ≤ 1000 ps. (b) Distribution of tstay of molecules with −2.0 ≤ zreach ≤ 0.0. (c) Distribution of tstay of molecules with −1.5 < zreach ≤ −0.5. Bar graphs with the time interval 20 ps are composed of the normalized number of molecules in each range of zreach.
Fig 7.
Relationship between normalized molecular velocities ζin and ζout of reflection molecules.
(a) Data points representing the relationship between ζin and ζout of reflection molecules. Sampling number of reflection molecules is 42, 359. (b) Bivariate histogram in the ζin–ζout coordinate plane. (c) Molecular velocity distribution functions of reflection molecules for the normalized incident velocity ζin and normalized outgoing velocity ζout.
Fig 8.
Relationship between zreach and normalized incident velocity ζin of molecules.
(a) Data points representing the relationship between zreach and ζin of all sampling molecules. (b) Bivariate histogram in the zreach–ζin coordinate plane. (c) Molecular velocity distribution functions of reflection molecules whose zreach values lie in zreach > −1.0 and condensation/evaporation molecules whose zreach values lie in zreach ≤ −1.0.
Fig 9.
(a) Time evolution of Jref in the present MD study; (b) condensation coefficient for each range of incident velocity ζin.