A polarizable force field (PFF) using multiple fluctuating charges per atom, ABEEMσπPFF, is presented in this work. The fluctuating partial charges are obtained from theelectronegativity equalization principle applied to the decomposition scheme of atom-bond regionsinto multiple charge sites: atomic, lone-pair electron, and σandπbond regions. These multiplepartial charges per atom should better account for the polarization effect than single atomiccharge in other PFFs. To evaluate the PFF, structural and energetic properties for some organicand biochemical systems, including rotational barriers; binding energies of base pairs; abase-base interaction in a B-DNA decamer; and interaction energies of ten stationary conformersof a water dimer, peptides, and bases with water molecules, have been calculated and comparedwith the experimental data orab initioMP2 results. Molecular dynamics simulations using thePFF have been performed for crambin and BPTI protein systems. Better performances inmodeling root-mean-square deviations of backbone bond lengths, bond angles, key dihedralangles, the coordinate root-mean-square shift of atoms, and the distribution of hydrogen bondshave been observed in comparison with other PFFs. These results indicate that the fluctuatingcharge force field, ABEEMσπ/MM, is accurate and reliable and can be applied to wide rangesof organic and biomolecular systems.
