OS100: A Benchmark Set of 100 Digitized UV–Visible Spectra and Derived Experimental Oscillator Strengths

Excited-state quantum chemical calculations usually report excitation energies and oscillator strengths, f, for each electronic transition. On the other hand, UV–visible spectrophotometric experiments measure energy-dependent molar extinction/attenuation coefficients, ε­(v), that give absorption band line shapes when plotted. ε­(v) and f are related, but this relation is complicated by broadening and solvation effects. We fitted and integrated 100 experimental UV–visible spectra to obtain 164 fexp values for absorption bands appearing in these spectra. The 100 UV–visible spectra belong to solvated organic molecules ranging in size from 6–34 atoms. We estimated uncertainties in the fitting to indicate confidence level in the reported fexp values. The corresponding computed oscillator strengths (fcomp) were obtained with time-dependent density functional theory and a polarizable continuum solvent model. By expressing experimental and computed absorption strengths using a common quantity, we directly compared fcomp and fexp. Although fcomp and fexp are well correlated (linear regression R2 = 0.921), fcomp in most cases overestimated fexp (regression slope = 1.34). The agreement between absolute fcomp and fexp values was substantially improved by accounting for a solvent refractive index factor, as suggested in some derivations in the literature. The 100 digitized UV–visible spectra are included as plain text files in the Supporting Information to aid in benchmarking computational or machine learning methods that aim to simulate realistic UV–visible absorption spectra.