A sequential MC/TD-DFT study of the solvatochromic shift of the pyridinium-N-phenoxide betaine dye in water using standard and long-range corrected functionals

► TD-DFT excitation energies of the ortho-betaine in vacuum and water are presented. ► The calculations are performed with standard and long-range corrected functionals. ► It found that the π-π∗ transition as the responsible by the optical properties. ► The experimental shift is reproduced after the inclusion of solute polarization.