Similar arguments can be applied for [(bipy)AuBr] + . Its equilibrium geometry of [(bipy)AuBr] +at all tested levelscorresponds to a C2v minimum, for which the calculated oscillator strength of the b2 transition is also very low, f ≈ 10 -4 (Table ). However, a relaxed scan of the N1-Au-Br tilt angle reveals that the energy of the system changes only very little (< 4 kJ.mol -1 for 20 degrees), while the intensity of the a' transition strongly raises, by ~100 times for the same (20 degrees) tilt, c.f. Table . The calc (a) calculated then raises to 754 nm (1.64 eV), relatively far from the experimental value of 663 nm (1.87 eV). Inclusion of spin-orbit coupling in calculations may decrease the predicted value by few tens of nm as shown in Table . All in all, we qualitatively demonstrated the sensitivity of the computed intensities on the small structural changes of the studied complexes. -665(0.01) 637