Photochromism is a light-induced molecular process that is likely to find its way into future optoelectronic devices. In further optimization of photochromic materials, light-induced conversion efficiencies as well as reaction times can usually only be determined once a new molecule was synthesized. Here we use nonadiabatic ab initio molecular dynamics to study the electrocyclic reaction of diarylethenes, comparing normal- and inverse-type systems. Our study highlights that reaction quantum yields can be successfully predicted in accord with experimental findings. In particular, we find that inverse-type diarylethenes show a significantly higher reaction quantum yield and cycloreversion on times typically as short as 100 fs.