Searching for various melting scenarios of 2D crystals

In contrast to three-dimensional (3D) crystals that melt via a first-order transition, two-dimensional (2D) crystals can exhibit various melting scenarios under different temperatures, pressures, and particle interactions, particularly when they can form partially ordered intermediate phases between crystal and liquid. The existing 2D melting theories predict some scenarios, but do not exclude other possibilities. A recent simulation observed five melting scenarios including two new types by tuning the shape of polygonal particles.