Influence of the crystal packing in singlet fission: one step beyond the gas phase approximation† Luis Enrique Aguilar Suarez, a Coen de Graaf abc and Shirin Faraji *a Author affiliations * Corresponding authors a Theoretical Chemistry Group, Zernike Institute for Advanced Materials, University of Groningen, Nijenborgh 4, 9747 AG Groningen, The Netherlands E-mail: s.s.faraji@rug.nl b Department of Physical and Inorganic Chemistry, Universitat Rovira i Virgili, Campus Sescelades, C.