The charge response kernel with modified electrostatic potential charge model

The charge response kernel (CRK), partial derivativeQ(a)/partial derivativeV(b) was reformulated using a modified definition of the partial charge Q(a).The modifications could effectively prevent numerical instability of the partial charges based on the electrostatic potential, and thus eliminate spurious components of CRK due to the fitting problem. The modified CRK was directly derived via the coupled-perturbed Hartree-Fock equations. The performance of this modified CRK model was examined by applying it to some test molecules including ethanol, DMSO, chloroform, and trimethylamine.