Influence of an electric-field on the topological stability of the neutral lithium dimer

In this investigation, we seek to understand the role of non-nuclear attractors (NNAs) of the neutral Li-2 dimer subjected to an electric (+/- E) field that is directed parallel (+/- E-x) and perpendicular (+/- E-y) to the bond-path. The +/- E-x-fields and +/- E-y-fields are separately applied to the Li-2 molecular graph until the bond ruptures. The next generation quantum theory of atoms in molecules (NG-QTAIM) interpretation of bonding was constructed with the stress tensor sigma(r) eigenvectors on the Hessian of rho(r) molecular graph. The asymmetry induced by both the +/- E-y-field and +/- E-x-field was detected in terms of the rotation of the orthogonal triad of stress tensor sigma(r) eigenvectors {(e) under bar (1 sigma), (e) under bar (2 sigma), (e) under bar (3 sigma)} relative to the Cartesian coordinate frame. The orthogonal triad of Hessian of rho(r) eigenvectors {(e) under bar (1), (e) under bar (2), (e) under bar (3)} however, were only able to detect rotation induced by the high degree of asymmetry present for bent bond-paths induced by the +/- E-y-fields. Larger movement of the NNAs along the bond-path correlated with greater bond critical point (BCP) bond metallicity xi(r(b)). The effect of applying the +/- E-x-field was compared with unpublished results on neutral Li-2 subject to a stretching distortion. The lack of NNA motion along the bond-path for the stretching distortion correlated with a lower degree of bond metallicity xi(r(b)). The stress tensor sigma(r) eigenvectors have a unique ability to detect rotation relative to the Cartesian coordinate frame for high bond-path symmetry occurring for the bond-stretching distortion and application of the +/- E-x-field. Suggestions for future work are provided.

Automated summary

In this investigation, the role of non-nuclear attractors (NNAs) of the neutral Li-2 dimer under the influence of parallel and perpendicular electric fields was studied. The next generation quantum theory of atoms in molecules (NG-QTAIM) interpretation was used to analyze the bonding using the stress tensor sigma(r) eigenvectors. Asymmetry induced by the electric fields was detected through the rotation of the stress tensor eigenvectors relative to the coordinate frame. The motion of the NNAs along the bond-path was found to correlate with bond metallicity, and the effect of electric field was compared with a stretching distortion. The unique ability of the stress tensor eigenvectors to detect rotation in high-symmetry systems was highlighted.