where 𝐿 ( is the median pitch of the entire BCP dot array, 𝑥 ) NN ) and 𝑦 ) NN ) are the 𝑥, 𝑦 coordinates of the six nearest neighbours (sorted in a clockwise fashion) and 𝑥 ) * and 𝑦 ) * are the coordinates of the regular hexagonal (with a pitch equal to 𝐿 ( ) that minimizes the value of 𝑅 " . Further detail of how 𝑅 " is calculated is given in the Supporting Information. This effect of increased lattice deviations from perfect hexagonality is illustrated in Figure for an initial film thickness of 28.0 nm. At a low swelling degree of 1.6, the lattice has a very large number of point defects, but the number of defects sharply decreases as the swelling degree is increased to 1.8, at which point almost all of the point defects belong to the grain boundaries. However, as the swelling degree is further increased, a very subtle but important change can be observed in the 𝑅 " maps, where the map appears to be darker purple (higher registration error) despite a similar number of point defects/grain boundaries. This increase of registration error is due to the average value of 𝑅 " increasing due to increased fluctuations in the local hexagonal coordination shell of BCP dots. This increase in the average 𝑅 " for 6-fold coordinated sites is believed to be a result of the segregation strength decreasing as the swelling degree increases. The relationship between the changes in the global average of 𝑅 " and SVA conditions is shown in the Figure , which is computed by ML fitting of the measured 𝑅 " values.