HOMO and LUMO are acronyms for highest occupied m.pdf

angelcolluctions 78 views 2 slides Apr 09, 2023
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About This Presentation

HOMO and LUMO are acronyms for highest occupied molecular orbital and lowest
unoccupied molecular orbital, respectively. The energy difference between the HOMO and
LUMO is termed the HOMO-LUMO gap. HOMO and LUMO are sometimes referred to as
frontier orbitals.[1] Roughly, the HOMO level is to organic...


Slide Content

HOMO and LUMO are acronyms for highest occupied molecular orbital and lowest
unoccupied molecular orbital, respectively. The energy difference between the HOMO and
LUMO is termed the HOMO-LUMO gap. HOMO and LUMO are sometimes referred to as
frontier orbitals.[1] Roughly, the HOMO level is to organic semiconductors what the valence
band is to inorganic semiconductors and quantum dots. The same analogy exists between the
LUMO level and the conduction band. The atomic orbitals and molecular orbitals pictured above
require complicated calculations and assumptions that far exceed the equation shown for ?nlm.
Spartan calculates these orbitals as HOMOs or LUMOs. The HOMO (highest occupied
molecular orbital) is the valence orbital that received the last valence electron(s). The orbital
directly beneath the HOMO in energy is labeled HOMO(-1). The LUMO (lowest unoccupied
molecular orbital) is the empty orbital just above the HOMO. The orbital just above the LUMO
is labeled LUMO(+1). The \"1\" can be changed to 2, 3, 4, ... to create a complete set of all MOs
in the molecule. The HOMO and LUMO images (surfaces) created by Spartan can be
correlated/represented with the lines on a molecular orbital (MO) diagram. In this experiment,
you will be asked to create the MO diagrams complete with Spartan orbital surfaces for H2 + ,
H2, and H2 - . Spartan also can generate electron density surfaces. Electron density is the square
of the wave function (|?| 2 , or |?| 2 ). Squaring the wave function results in the loss of phase
information (i 2 = - 1). The lack of phase information is indicated in Spartan by the creation of
gray only density surfaces (Note: the \"electron\" is omitted in Spartan). The surface created
represents the relative size and shape of the molecule, atom, or ion being investigated.


Solution
HOMO and LUMO are acronyms for highest occupied molecular orbital and lowest
unoccupied molecular orbital, respectively. The energy difference between the HOMO and
LUMO is termed the HOMO-LUMO gap. HOMO and LUMO are sometimes referred to as
frontier orbitals.[1] Roughly, the HOMO level is to organic semiconductors what the valence
band is to inorganic semiconductors and quantum dots. The same analogy exists between the
LUMO level and the conduction band. The atomic orbitals and molecular orbitals pictured above
require complicated calculations and assumptions that far exceed the equation shown for ?nlm.
Spartan calculates these orbitals as HOMOs or LUMOs. The HOMO (highest occupied
molecular orbital) is the valence orbital that received the last valence electron(s). The orbital
directly beneath the HOMO in energy is labeled HOMO(-1). The LUMO (lowest unoccupied
molecular orbital) is the empty orbital just above the HOMO. The orbital just above the LUMO
is labeled LUMO(+1). The \"1\" can be changed to 2, 3, 4, ... to create a complete set of all MOs
in the molecule. The HOMO and LUMO images (surfaces) created by Spartan can be

correlated/represented with the lines on a molecular orbital (MO) diagram. In this experiment,
you will be asked to create the MO diagrams complete with Spartan orbital surfaces for H2 + ,
H2, and H2 - . Spartan also can generate electron density surfaces. Electron density is the square
of the wave function (|?| 2 , or |?| 2 ). Squaring the wave function results in the loss of phase
information (i 2 = - 1). The lack of phase information is indicated in Spartan by the creation of
gray only density surfaces (Note: the \"electron\" is omitted in Spartan). The surface created
represents the relative size and shape of the molecule, atom, or ion being investigated.
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