Modern nanotechnological revolution is based on the use of bistable molecules and molecular ensembles as basic elements of high-tech devices. In this work quantum-mechanical investigations of the potential surface merocyanine-spiropyran transformation were carried out. Under dark conditions, such transition will be possible when potential barrier with height ~ 0.7 eV is overcomed. Rotating the phenyl moiety relative to the plane of the molecule by 90 ° without simultaneously changing all other parameters of the molecule (optimization of the molecular structure) increases the molecule's energy by 1.376 eV
