ESP-Based Fitting Methods

More recently, efforts have been made to parametrize MTP coefficients with respect to the ESP itself [32, 39, 58, 113-115]. From Eq. 7.4, one readily observes the linear dependence of each MTP coefficient on the ESP. Optimizing MTP coefficients to best reproduce the ab initio ESP can thus be obtained from a simple linear least-squares fit over a number of discrete points r P around the molecule. We thus express the target function 

Fitting electrostatic parameters—and especially point charges— to the ESP is a comparatively old idea [116-118]. There are two main features associated with it  

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