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 Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

The total π-electron energy E of a conjugated hydrocarbon with n carbon atoms and m carbon-carbon bonds can be approximately calculated by means of the McClelland formula mn g E 2 ≈ , where g is an empirical fitting constant, g ≈ 0.9. It was claimed that the good quality of the McClelland approximation is a con- sequence of the fact that the π-electron molecular orbital energy levels are distribu- ted in a nearly uniform manner. It will now be shown that the McClelland ap- proximation does not depend on the nature of the distribution of energy levels, i.e., that it is compatible with a large variety of such distributions.

The McClelland approximation and the distribution of π-electron molecular orbital energy levels