Quantitative agreement between electron-optical phase images of WSe2 and simulations based on electrostatic potentials that include bonding effects

The quantitative analysis of electron-optical phase images recorded using off-axis electron holog- raphy often relies on the use of computer simulations of electron propagation through a sample. However, simulations that make use of the independent atom approximation are known to over- estimate experimental phase shifts by approximately 10%, as they neglect bonding effects. Here, we compare experimental and simulated phase images for few-layer WSe2. We show that a com- bination of pseudopotentials and all-electron density functional theory calculations can be used to obtain accurate mean electron phases, as well as improved atomic-resolution spatial distribution of the electron phase. The comparison demonstrates a perfect contrast match between experimental and simulated atomic-resolution phase images for a sample of precisely known thickness. The low computational cost of this approach makes it suitable for the analysis of large electronic systems, including defects, substitutional atoms and material interfaces.