The availability of experimental UV-vis spectra in vacuo for this chromophore ns. For each sampled snapshot, we used the OpenMolcas software to compute, at the cc-pVDZ level, RMS-CASPT2 (12,12) vertical transition energies for the first 3 states and SA(3)-CASSCF(12,12) S 0 → S 1 oscillator strengths, eventually retrieving the final UV-vis spectrum as a gaussian convolution of all data. The comparisons shown in Figure .d demonstrate that the JOYCE 3.0 description provides a much better agreement with experimental data. The position of the spectrum, attributable to the overall description of molecular geometry, is on top of experimental data, whereas GAFF is visibly more shifted. Moreover, JOYCE3.0 spectral width is also much closer to experiments, whereas, as expected from its too rigid structure, the general purpose description provides a significantly narrower spectrum. Based on these findings, the accuracy of the proposed QMD-FF appears as an appropriate starting point for subsequent studies of excited state dynamics.