Evaluation of the electrostatic potential and its derivatives in reciprocal space

2 Evaluation of the Electrostatic Potential and its Derivatives in Reciprocal Space 

1 The Electrostatic Potential by Fourier Summation of the Structure Factors 

Since the electrostatic potential and its derivatives are directly related to the charge density, it is not surprising that they also can be obtained by Fourier summation 

The electrostatic potential is defined in reciprocal space via the Fourier transform expression 

In analogy to the definition of the total charge density, we define the total structure factor Ftotal(H), which includes both the nuclei and the electrons, and is, excluding thermal effects, given by 

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