Concerning the energy of frontiers orbitals (HOMO and LUMO) of a molecule, it can be possible to found these energies to be positives values ?
thank you.
Sure they can. Start adding electrons to the molecule and eventually they HOMO and LUMO will be positive.
Dear Brahim,
Formation of a stable molecular system is a direct consequence of special arrangement of electrons and nuclei. In such a system electrons are under attraction of nuclei otherwise system does not remain stable. Consequently, all occupied molecular levels should have negative energy; i.e., HOMO, the highest occupied molecular orbital, never presents a positive value. For unoccupied levels such as LUMO and LUMO+n (n=1,2,..) the mentioned limitation is not necessarily exist and, hence, they are allowed to be positive. Note that if LUMO in a system to be a bonding orbital, its energy should be negative. On the other hand, if LUMO is associated with a non-bonding or anti-bonding orbital, corresponding energy will be positive.
Best regards,
Saeed
Generally, people say MO is bonding or antibonding based on their lobes. How someone can say that?
Saeedreza Emamians comments about the LUMO are incorrect. A negative LUMOs energy being positive or negative contains no information about it being a 'bonding' or 'anti-/non-bonding' interaction.
- Badges
- Science topic