where 𝛷(𝑥, 𝑦) is the sample phase shift, 𝜎 is the interaction parameter, 𝑉(𝑥, 𝑦) is the projected potential of the entire sample. The interaction parameter 𝜎 is given by σ = 2𝜋𝑚𝑒𝜆 ℎ 2 , where m is the relativistic mass of the electron, e is the elementary charge,  is the wavelength of the electrons, and h is the Planckʼs constant. Eq. (S1) can further be approximated by the first order Taylor series as