Current thoughts:
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Except for one torsion scan (scan1), other torsion scans from the smaller basis set(DZVP) agree well enough with those from larger basis sets(def2-TZVP(-f), cc-pVTZ(-f))
Current choice of method is not unreliable, but some cases(such as scan1) support our concerns on the size of the current basis set to some extent.
(2) Scatter plots of cis/trans energy differences w.r.t OFF AM1 WBO/ DFT WBO
To see if the usage of WBO interpolated parameter for the spring constant of one-fold cosine function(which is for describing the cis/trans conformation preference), linear dependences of cis/trans energy differences and WBOs from different methods(OFF AM1-Wiberg method, DFT) were plotted.
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Note that there’s a disagreement of the order of AM1 WBOs with the order of WBOs obtained from DFT.
(3) Two approaches to estimate covalent contribution of QM energies and scatter plots of covalent contribution of cis/trans energy differences w.r.t OFF AM1 WBO/ DFT WBO
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