Larger molecules have smaller HOMO-LUMO Gaps?

by Hyo X
Tags: gap, homo-lumo, molecules
Hyo X
Hyo X is offline
Aug19-13, 01:53 PM
P: 37
Is it true that in general, larger molecules will have smaller HOMO-LUMO gaps?

In this case consider that we are comparing long vs short saturated molecules,
and long vs. short conjugated molecules.
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DrDu is offline
Aug20-13, 01:57 AM
Sci Advisor
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If it were true in general, there wouldn't be any insulators.
tadchem is offline
Aug20-13, 07:33 AM
P: 61
When it comes to chemistry, in general there are no reliable generalities.

DrDu is offline
Aug20-13, 02:10 PM
Sci Advisor
P: 3,361

Larger molecules have smaller HOMO-LUMO Gaps?

In saturated molecules, the gap will hardly depend on system size while in conjugated systems, it will decrease with system size. However, in larger conjugated molecules, new gaps may open due to the Peierls instability.

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