Figure 4

The optimized structures of 3D electron density map (left) and 2D electron density map (right) at 0.025 Å−3 iso-surface for the optimized structures of the a-C films; (a) Pure, (b) B doped, (c) N doped, and (d) Cl doped a-C films. Drawings are produced by VESTA38 (ver. 3.4.7) software (https://jp-minerals.org/vesta/en/download.html).