Theoretical prediction of pH-dependent electronic spectra in aqueous solution: A combinational application of QM/MM calculations and constant-pH simulations with configuration-selection scheme

•A CpH method was developed with configuration-selection (CS) scheme and QM/MM method.•CS-CpH method predicts very well pH-dependent electronic spectra in aqueous solution.•Electronic spectra and isosbestic point of p-nitrophenol were reproduced very well.•The method is promising for complex molecules without Henderson–Hasselbalch relation.