How believable are molecular dynamics simulations?
In classical molecular dynamics, atoms are simplified as point masses and the interatomic interactions are simplified using some mathematical functions, which simulate the effect of the interactions to a qualitative accuracy. These simplifications strip off the basic complexity of individual atoms as quantum entities. But under the conditions that we care about the collective behaviors of many atoms, it is an acceptable simplification. Indeed, for many nano-scale phenomena we are interested in physics, chemistry and biology, a coarse-grained atomic model serves decently. To give you a quick idea, gas laws can be nicely demonstrated by this grade of models without having to worry about if we have missed the accuracy of atomic orbitals. The problems that follow as we try to make science comprehensible at different levels are quite general and subtle. It is probably hard for students to understand what a coarse-grained approach is and the necessities of using it in presenting knowledge. I
