Demixing cascades in cluster crystals.

Area of Science:

• Condensed Matter Physics
• Statistical Mechanics
• Materials Science

Background:

• Cluster crystals feature multiple soft-core particles per lattice site.
• Increasing density at zero temperature can trigger isostructural phase transitions.
• These transitions involve changes in site occupancy by a single particle.

Purpose of the Study:

• Investigate demixing cascades in soft-core particle systems.
• Analyze phase transitions as a function of particle softness (n).
• Determine critical parameters (temperature, pressure, chemical potential).

Main Methods:

• Utilized tailored Monte Carlo simulation techniques.
• Studied systems with generalized exponential potentials: u(r) = ε exp[-(r/σ)(n)].
• Performed cell model calculations at zero temperature for validation.

Main Results:

• Critical temperature and pressure display non-monotonic dependence on the softness parameter n.
• Critical chemical potential shows monotonic behavior with respect to n.
• Observed that transitions are preempted by melting as n approaches 2.

Conclusions:

• The study provides insights into the complex phase behavior of soft-core matter.
• Non-monotonic critical parameters highlight the nuanced effects of particle softness.
• Melting can dominate over clustering transitions at high densities and specific softness values.