Supporting Information for: “Dynamics of Azobenzene Dimer Photoisomerization: Electronic and Steric Eﬀects” Evgenii Titov, † Giovanni Granucci, ‡ Jan Philipp G¨ otze, † Maurizio Persico, ‡ and Peter Saalfrank *,† Theoretical Chemistry, Institute of Chemistry, University of Potsdam, Karl-Liebknecht-Straße 24-25, 14476 Potsdam, Germany, and Department of Chemistry and Industrial Chemistry, University of Pisa, via Moruzzi 13, 56124 Pisa, Italy E-mail: peter.saalfrank@uni-potsdam.de * To whom correspondence should be addressed † Theoretical Chemistry, Institute of Chemistry, University of Potsdam, Karl-Liebknecht-Straße 24-25, 14476 Potsdam, Germany ‡ Department of Chemistry and Industrial Chemistry, University of Pisa, via Moruzzi 13, 56124 Pisa, Italy S1