The file 1,2-dimethylcubane-step1-profile.Prof.M0001 is the output file from the computational program Spartan, which was used to model the extent to which the scissile C-C bond breaking reaction along an edge of cubane is coupled to the mechanical force vector applied to different potential pulling positions (1,2 vs 1,3 vs 1,4 attachments). The analysis comprises calculating how the distance between the putative pulling attachments in each case changes as the reaction proceeds from ground state to transition state, and to use that change in distance as a first order approximation for the distance that a coupled, overstretched polymer chain can relax as the reaction proceeds.  

We restrict and vary the CÉC distance along the scissile bonding coordinate, increasing it in 0.5  increments. The output geometries in the file were used to then calculate the distance between: the separation of methyl groups attached to the 1,2 scissile positions (change in 1,2 attachment), an alpha-methyl carbon relative to beta-CH corresponding to 1,3 pulling (change in 1,3 attachment), and alpha-methyl carbon relative gamma-CH (corresponding to 1,4 attachment). All calculations are performed in Spartan using DFT with B3LYP functionals and a 6-31G* basis set.