| Autor: |
Tsiok EN; Institute of High Pressure Physics RAS, Kaluzhskoe Shosse, 14, Troitsk, Moscow 108840, Russia., Fomin YD; Institute of High Pressure Physics RAS, Kaluzhskoe Shosse, 14, Troitsk, Moscow 108840, Russia., Gaiduk EA; Institute of High Pressure Physics RAS, Kaluzhskoe Shosse, 14, Troitsk, Moscow 108840, Russia., Tareyeva EE; Institute of High Pressure Physics RAS, Kaluzhskoe Shosse, 14, Troitsk, Moscow 108840, Russia., Ryzhov VN; Institute of High Pressure Physics RAS, Kaluzhskoe Shosse, 14, Troitsk, Moscow 108840, Russia., Libet PA; Institute of High Pressure Physics RAS, Kaluzhskoe Shosse, 14, Troitsk, Moscow 108840, Russia., Dmitryuk NA; Bauman Moscow State Technical University, 2nd Baumanskaya Street 5, 105005 Moscow, Russia., Kryuchkov NP; Bauman Moscow State Technical University, 2nd Baumanskaya Street 5, 105005 Moscow, Russia., Yurchenko SO; Bauman Moscow State Technical University, 2nd Baumanskaya Street 5, 105005 Moscow, Russia. |
| Abstrakt: |
Monolayer and two-dimensional (2D) systems exhibit rich phase behavior, compared with 3D systems, in particular, due to the hexatic phase playing a central role in melting scenarios. The attraction range is known to affect critical gas-liquid behavior (liquid-liquid in protein and colloidal systems), but the effect of attraction on melting in 2D systems remains unstudied systematically. Here, we have revealed how the attraction range affects the phase diagrams and melting scenarios in a 2D system. Using molecular dynamics simulations, we have considered the generalized Lennard-Jones system with a fixed repulsion branch and different power indices of attraction from long-range dipolar to short-range sticky-sphere-like. A drop in the attraction range has been found to reduce the temperature of the gas-liquid critical point, bringing it closer to the gas-liquid-solid triple point. At high temperatures, attraction does not affect the melting scenario that proceeds through the cascade of solid-hexatic (Berezinskii-Kosterlitz-Thouless) and hexatic-liquid (first-order) phase transitions. In the case of dipolar attraction, we have observed two triple points inherent in a 2D system: hexatic-liquid-gas and crystal-hexatic-gas, the temperature of the crystal-hexatic-gas triple point is below the hexatic-liquid-gas triple point. This observation may have far-reaching consequences for future studies, since phase diagrams determine possible routes of self-assembly in molecular, protein, and colloidal systems, whereas the attraction range can be adjusted with complex solvents and external electric or magnetic fields. The results obtained may be widely used in condensed matter, chemical physics, materials science, and soft matter. |
