PES scans, with r as the reaction coordinate, were performed to acquire reaction profiles for the formation of various rotamers (see Figure ). As shown in Figure , the r-dependent PES curves calculated with ωB97X-D3(BJ) remain accurate with respect to CCSD(T)@MP2, with a mean absolute error of 1.15 kcal mol -1 between the two methods. Both sets of CCSD(T) calculations had a mean average T 1 diagnostic value 50 of 0.016 and a standard deviation of 0.001, indicating their reliability. The dependence of T 1 on r can be seen in Figures ) and S1(c).