Experimenters can create molecules with computers before trying to make them in the lab, while theorists can test their theories about how atoms form molecules.
Physics equations can describe any piece of matter.
If you work at it hard enough, you can describe any molecule with equations, and then use more equations to see how it is shaped and how it reacts with other molecules. You probably think of molecules as tiny, solid, maybe ball-shaped things. But molecules come in different shapes and sizes, and just like a guitar string, they can vibrate. This data describes this vibrating molecule.