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

We propose a self-contained theoretical methodology to predict the pH effects on the molecular electronic spectra in aqueous solution, combining our recently developed the configuration-selection (CS) constant-pH (CpH) simulation (CS-CpH) method with quantum mechanics/molecular mechanics (QM/MM) method. By computationally sampling many protonation state transitions by CS-CpH simulations and estimating the electronic energies by QM/MM calculations, we can obtain the theoretical description of the pH dependent electronic spectra. As an example, we applied the present methodology to para-nitrophenol (pNP) in aqueous solution, and demonstrated that the method could successfully reproduce the electronic transition energies and the isosbestic point.

Automated summary

We propose a self-contained theoretical methodology to predict the pH effects on the molecular electronic spectra in aqueous solution. By combining the configuration-selection constant-pH simulation method with quantum mechanics/molecular mechanics method, we can obtain the theoretical description of the pH dependent electronic spectra.