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The problem of generating high-quality atomic charges valid over a range of conformations has been addressed using two related methods which both employ a constrained minimizationof the difference between the quantum mechanical and classical MEP (molecularelectrostatic potential) with respect to the atomic charges. The first method involves determining the MEP and constraining the charges to reproduce the dipole at an alternative geometry. The second method involves determining the MEP for each conformation of interest and weighting the MEP for each conformation according to the appropriate Boltzmann factor. These methods offer considerable improvement over averaging the charges obtained at each conformation. The improvement in the performance of these multiple conformation MEP derivedcharges is illustrated by studying the variation of the classical dipole with conformation and comparing …