The ABEEM/MM (atom-bond electronegativity equalization fused into molecular mechanic) fluctuating charge force field was used in molecular dynamic simulation for N-methylacetamide (NMA) aqueous solution. The electrostatic potential is obtained from the fixed atomic-center charges for the classi-cal force field. In the ABEEM/MM model, comparing to the classical force field, the partial charges are al-lowed to fluctuate in the same molecule in response to the environment. In order to describe the charge population reasonably, the important non-atomic-center charge sites (chemical bond and lone pair) are added into this model. The CPU time is not increased larger than other polarized force field. The resulting data of molecular dynamic simulation were analyzed for pure NMA and its aqueous solution, such as the radial distribution function, heat of vaporization, dipole moments, etc. All in all, the relevant quantities are well in agreement with those of the corresponding experimental and other polarized model. The charge transfers of intramolecule and the polarization between solvent and solute are reasonably described with the ABEEM/MM model.

Key words: atom-bond electronegativity equalization fused into molecular mechanic (ABEEM/MM), N-methylacetamide, polarized force field, molecular dynamic simulation