In physics, phase transition is the change of substances. In chemistry, chemical reaction. For example, catalyst and glue.
There are two approaches of Simulation for phase transition and chemical reaction. One is the macro view. For example, using reaction-velocity formulation. Th other is micro view . For example, Molecular Dynamics .
Phase transition is a transition among three phase, solid, liquid, and vapor. Phases changes on peculiar temperture. The state on the temperture is called "critical state".
There are othre transitions. For example, "grass transition" and "superconductivity".
Catalyst helps chemical reaction. Even if the chemical reaction does not occur on the normal condition, it occurs by catalyst. So in chemical engineering, the discovery of new catalyst brings enormous money.
Catalyst itself does not changes. It is said that it loweres the barrier of energy of the chemical reaction.
There are two types of the glue
One enters unevennness of faces. The other dissolves the face.