A Novel/Old Modification of the First Zagreb Index

Akbar Ali, Nenad Trinajstić

In the paper [I. Gutman, N. Trinajstić, Chem. Phys. Lett. 17 (1972), 535], it was shown that total $\pi$-electron energy ($E$) of a molecule $M$ depends on the quantity $\sum_{v\in V…