Induced dipole moment and atomic charges based on average electrostatic potentials in aqueous solution

Abstract

A Monte Carlo quantum mechanical and molecular mechanical (QM/MM) simulation method using the combined Austin model 1 (AM1) and TIP3P potential is proposed to evaluate the average molecular electrostatic potentials (MEP) in aqueous solution. It was demonstrated that the average MEP in water can provide a quantitative account of the solvent polarization effect on molecular dipole moments and atomic charges. The computed induced dipole moments from the Monte Carlo AM1/TIP3P simulation method were found to be in good agreement with those predicted by continuum self‐consistent reaction field theory using the AM1 and 6‐31G(d) wave functions. The findings also indicate that the minimal basis set adopted by the AM1 method can capture the solvent effect effectively. Finally, good correlations in the MEP‐fitted charges were obtained between different methods. These results should be useful for developing polarizable intermolecular potential functions (PIPF).