The measured electron structure factors Ug (Fourier coefficients of the crystal potential) are converted to X-ray structure factors Fg (Fourier coefficients of the electron density) with the Mott-Bethe formula 
. 811h'-h20.s2 F. = "'Z.T e-2n.g·r;- -u U. . g f I l,g rmee2 g (1)
The sum goes over all atoms, where Z; and T;,g are the atomic number and temperature factor of atom i, respectively. Q is the unit cell volume, s = sin(} I A the scattering angle andy= 1 + E01(mec?) a relativistic correction, with E0 being the acceleration voltage of the microscope.