Bonding analysis at HOMO, could you please give me some hints.

In summary, the paper discusses the contribution of atomic orbitals to the highest occupied molecular orbital (HOMO) in ultrathin ZnO nanowires under uniaxial compression. The analyses show that the bonding at Gamma-point is mainly from O pz and Zn dz2 states, and this bonding is stronger at Gamma-point than at E or F points. The authors also explain the difference between the equivalent spatial orbitals in isotropic space and in a covalent bonding network. They suggest using a computational quantum electronic structure package to track the contribution of specific orbitals in such systems.
  • #1
zhaohs
2
0
Hi all,

Currently, I'm reading the paper: Direct to indirect band gap transition in ultrathin ZnO nanowires under uniaxial compression [APPLIED PHYSICS LETTERS 94, 113114, 2009].

You can download this paper from the following url:

http://h1.ripway.com/zhaohs/Direct ...ansition in ultrathin ZnO nanowires under.pdf

At the top of page 3, the author said:

--------------
A detailed analysis on the characteristics of atomic orbital contribution of the
highest occupied molecular orbital (HOMO) shows that
bonding at Gamma-point is mainly contributed from the O pz and
Zn dz2 states, with equal components from all the six Zn and
O in the supercell. For point E and F in Fig. 4, the key
bonding characteristics are also the O pz and Zn dz2, but from
only two (L=0.48 nm) or four (L=0.47 nm) Zn and O atoms.
The analyses indicate that bonding of HOMO at
Gamma-point is much stronger than that at E or F point. Therefore,
during uniaxial compression, the energy lowering at Gamma-point
will be much faster than that at E or F point.
--------------

But I cann't figure out what calculations should I performed in order to obtain the above information within siesta.

Furthermore, the author said that the bonding are mainly contributed from O pz and Zn dz2. But in my mind, all of the three sub-orbitals of p (px,py, pz) are exactly equivalent, and that is also the case for the five sub-orbitals of d (dz2, dxz, dxy, dx2-y2, dyz). So, how should they know the bonding are mainly contributed from O pz and Zn dz2?

Could you please give me some hints? Thanks in advance.

Regards.
 
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  • #2
zhaohs said:
Hi all,

Currently, I'm reading the paper: Direct to indirect band gap transition in ultrathin ZnO nanowires under uniaxial compression [APPLIED PHYSICS LETTERS 94, 113114, 2009].

You can download this paper from the following url:

http://h1.ripway.com/zhaohs/Direct ...ansition in ultrathin ZnO nanowires under.pdf

At the top of page 3, the author said:

--------------
A detailed analysis on the characteristics of atomic orbital contribution of the
highest occupied molecular orbital (HOMO) shows that
bonding at Gamma-point is mainly contributed from the O pz and
Zn dz2 states, with equal components from all the six Zn and
O in the supercell. For point E and F in Fig. 4, the key
bonding characteristics are also the O pz and Zn dz2, but from
only two (L=0.48 nm) or four (L=0.47 nm) Zn and O atoms.
The analyses indicate that bonding of HOMO at
Gamma-point is much stronger than that at E or F point. Therefore,
during uniaxial compression, the energy lowering at Gamma-point
will be much faster than that at E or F point.
--------------

But I cann't figure out what calculations should I performed in order to obtain the above information within siesta.

Furthermore, the author said that the bonding are mainly contributed from O pz and Zn dz2. But in my mind, all of the three sub-orbitals of p (px,py, pz) are exactly equivalent, and that is also the case for the five sub-orbitals of d (dz2, dxz, dxy, dx2-y2, dyz). So, how should they know the bonding are mainly contributed from O pz and Zn dz2?

Could you please give me some hints? Thanks in advance.

Regards.

Well, I don't know what siesta is .. I guess it's some sort of solid-state computational physics package .. so I'm afraid I can't be much help there.

However, I can perhaps help with your confusion about the spatial orbitals. The spatial orbitals (i.e. px, py, pz, or the 5 d-orbitals) are only "equivalent" (I assume you meant degenerate), when an atom is in isotropic space. In this case, the atoms are participating in a covalent bonding network, and thus are most definitely NOT in isotropic space. As to how the authors know specifically that it is the pz and dz[sup2[/sup] orbitals contributing .. that is one of the things you can keep track of with a computational quantum electronic structure package.
 
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FAQ: Bonding analysis at HOMO, could you please give me some hints.

1. What is HOMO in bonding analysis?

HOMO stands for Highest Occupied Molecular Orbital. It is the highest energy orbital that is occupied by electrons in a molecule.

2. How is HOMO determined in bonding analysis?

HOMO can be determined through computational methods such as molecular orbital theory or quantum chemistry calculations.

3. What does HOMO indicate in bonding analysis?

HOMO provides information about the stability and reactivity of a molecule. A lower energy HOMO indicates a more stable molecule, while a higher energy HOMO indicates a more reactive molecule.

4. How is HOMO related to bonding in a molecule?

HOMO describes the bonding between atoms in a molecule. It represents the highest energy level where electrons are involved in bonding interactions.

5. Can HOMO be used to predict chemical properties?

Yes, the energy and shape of the HOMO can provide insight into the chemical properties of a molecule, such as its reactivity and ability to form bonds with other molecules.

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