Charge density difference in ( 1¯10 ) plane: (a) system with single Re atom at Al site in γ′ phase, which corresponds to model S3 in Fig. 2; (b) system with single Re atom at Ni site in γ′ phase, which corresponds to model S3′ in Fig. 2. The contour lines denote charge accumulation (solid line) and depletion (dashed line) and are plotted with an increment of 0.0027 e/a.u.³