The Uσ-space distortion set {Cσ,Fσ,Aσ} as a molecular similarity measure
We created Sa and Ra stereoisomers of glycine by applying an electric (E) -field to induce symmetry-breaking changes to the length of the C-H bonds attached to the alpha carbon (C1) atom, see Table 3(a-b) and Figure 2 . We found that reversal of the E -field caused a reversal of the chirality Cσ of the Sa stereoisomer fromSσ to Rσ , except for the high E -field = +200×10-4 a.u., which distorted the structure to the extent of inducing an intramolecular hydrogen bond. The corresponding reversal of the chirality Cσ also occurred for the Rastereoisomer. The E -field amplification EAσ is found to increase with the application of a non-structurally distortingE -field, demonstrating that control of the chirality Cσ of glycine is possible in the case of negligible structural distortion.
The largest magnitudes of bond-flexing Fσ occur for both the Sa and Ra stereoisomers atE = -100×10-4 a.u. (Fσ ≈ 1.0) and are approximately three times greater than for the absence of theE -field (Fσ ≈ 0.33), see Table 2(b) . The lowest magnitudes of the bond-flexing Fσ occur atE = +100×10-4 a.u. (Fσ ≈ 0.1) for both the Sa and Ra stereoisomers and are approximately a third of those in the absence of theE -field (Fσ ≈ 0.33). This indicates that atE = -100×10-4 a.u. and E = +100×10-4 a.u., the Sa and Ra stereoisomers experience the least and greatest degree of torsional C1-N7 BCP bond-strain, respectively.
Table 3(a). The maximum stress tensor projections{ bond-twist max, bond-flexingmax, bond-anharmonicitymax}, of the dominant torsional C1-N7 BCP for the electric field induced Sa and Ra stereoisomers of glycine are presented; all entries have been multiplied by 103, also see the caption of Table 1(a).
{ bond-twistmax, bond-flexingmax, bond-anharmonicitymax}
Sa Ra