麻豆淫院

Matter is either gas, liquid or solid based on how its molecules respond to temperature and pressure. But what if the building blocks are self-spinning particles instead of ordinary molecules? Theoretical physicists found out what determines the phase of those artificial materials. The research has been reported in PNAS.

When water reaches 100 掳C, it transitions to a gas phase, at least at sea level. Removing air pressure causes water to boil at colder temperatures. It is clear that materials made up of ordinary molecules take on a phase depending on temperature and pressure. Leiden theoretical physicist Prof. Vincenzo Vitelli wondered what would happen if materials had self-spinning dimers as building blocks instead.

Simulation

To this end, first authors Benny van Zuiden and Jayson Paulose simulated self-spinning dimers in silico and studied how they organize themselves. By applying a gradually increasing pressure on them, they saw the system change from an ordered state to a very chaotic state.

The figure below (left) shows a beautifully ordered state, with dimers neatly forming a triangular crystal lattice. Moreover, the relative orientation of nearby particles are locked as they spin.

At right, the concentration is so high that the system gets stuck in a glassy phase. Remarkably, there is a liquid phase in between. Usually, a substance becomes more solid as its density increases. Here, the opposite happens.

Liquid

So how can there be a liquid state? With low density, the dimers have plenty of room to move as they wish and stay in sync, like a group of stage dancers. When the stage is too small, dancers will bump in to each other and move chaotically, as particles in a liquid. However, if the stage gets so tiny that the dancers are unable to move, they get stuck in a disordered configuration reminiscent of a glass.