Aiming at the improvement of the photochemical performance of dithienylethenes, we present an analysis of the parameters that influence the quantum yield. We address some basic features of the ground-state potential energy surface of the photochromic dithienylethenes, showing the existence of three to five rotational conformers. Among those, only one is reactive. The energetical ordering and energy gaps between different conformers are investigated. The calculated results were compared to X-ray, proton NMR, and absorption spectra.