Restricted open-shell Kohn–Sham theory for π–π* transitions. II. Simulation of photochemical reactions

We present first principles molecular dynamics simulations of the photochemistry of butadiene and cyclohexadiene. The excited state is described with restricted open-shell Kohn–Sham theory. We observe cis–trans isomerizations for 1,3-butadiene and conrotatory ring opening of cyclohexadiene. The excitation of a sample of several butadiene molecules leads to the formation of an excimer.