Moreover, superconductivity has been reported in several GICs with chemical formulae MC6 (M = Ca , Sr , Ba , and Yb ) and MC8 (M = K, Rb, and Cs ). Figure shows the crystal structures and compositions of GICs reported experimentally under ambient pressure . The GICs are typically characterized by their stacking order and compositions. Three types of stacking structures (A, AA, and AAA stacking) have been reported for the MC6 composition. However, no studies have reported the A or AA stacking for the MC8 composition to date, and only the AAA and AAAA stacking have been reported. Although several studies have suggested the synthesis of CFx (2 < x < 5) as GICs , their treatment in the same category as other GICs is controversial because their bonding is relatively covalent and their structure is different from that of others . Conversely, in computational science, various correction methods that include longrange dispersive interaction, particularly van der Waals (vdW) interaction, have been proposed using the first-principles calculation based on density functional theory (DFT).