A.  Amat, Mosconi, E., Ronca, E., Quarti, C., Umari, P., Nazeeruddin, M. K., Graetzel, M., and De Angelis, F., ?Cation-Induced Band-Gap Tuning in Organohalide Perovskites: Interplay of Spin-Orbit Coupling and Octahedra Tilting?, Nano Letters, vol. 14, pp. 3608?3616, 2014.