English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Plus monthly

Global: Zendy Tools annual

Global: Zendy Tools monthly

Global: Zendy Free Plan

Despite the long history of spectroscopic studies of the C$_2$ molecule,fundamental questions about its chemical bonding are still being hotly debated.The complex electronic structure of C$_2$ is a consequence of its densemanifold of near-degenerate, low-lying electronic states. A global multi-statediabatic model is proposed here to disentangle the numerous configurationinteractions within four symmetry manifolds of C$_2$ ($^{1}\Pi_g$, $^{3}\Pi_g$,$^{1}\Sigma_u^+$, and $^{3}\Sigma_u^+$). The key concept of our model is theexistence of two "valence-hole" configurations,$2\sigma_g^22\sigma_u^11\pi_{u}^33\sigma_g^2$ for $^{1,3}\Pi_g$ states and$2\sigma_g^22\sigma_u^11\pi_{u}^43\sigma_g^1$ for $^{1,3}\Sigma_u^+$ statesthat derive from $3\sigma_g\leftarrow2\sigma_u$ electron promotion. Thelowest-energy state from each of the four C$_2$ symmetry species is dominatedby this type of valence-hole configuration at its equilibrium internuclearseparation. As a result of their large binding energy (nominal bond order of 3)and correlation with the 2s$^2$2p$^2$+2s2p$^3$ separated-atom configurations,the presence of these valence-hole configurations has a profound impact on the$global$ electronic structure and unimolecular dynamics of C$_2$.

Diabatic valence-hole states in the C$_2$ molecule: "Putting Humpty Dumpty together again"