[quyenp]

Hi everyone, I just consider how to determine L in this equation En=(n²h²)/8mL², Which L is the length of 1-D box.
For example in octatetraene: L = (N+1)d but in butadiene L =N.d, which N, d is respectively number of Cacbon and d is the average Cacbon-Cacbon bond length in hydrocarbon.
Thank you!

[Enthalpy]

I don't see neither why N+1 versus N. Does you book suggest a reason?

The L is a bit arbitrary and tweaking it somewhere around N×d must help fit the measures, but I wouldn't like to change this factor between a compound and an other.

N+1 would give the π electrons more room than the (conventional) molecule length including the atomic radii, so my gut feeling favours N×d. And that would even be the unfolded length of the molecule.