Comment by tsimionescu

> Our models use single atoms (or single molecules), and for those we have pretty good models that we can solve numerically, at least.

We can only solve these with assumptions, like assuming that protons or neutrons are indivisible particles with experimentally determined sizes and perfectly spherical shapes - even though we know very well that they are in fact collections of quarks and gluons whose size and shape is fully determined by more fundamental intercations. We are nowhere near a point where we could compute anything about a whole hydrogen atom using only the standard model and no other assumptions. Quantum chromodynamics is far to complex to allow for a perfect simulation like this.