View source for Rep:Mod:01365318,XYK17

== NH<sub>3</sub> ==

Molecule: NH<sub>3</sub>

Calculation method: RB3LYP

Basis set: 6-31G(d.p)

Final energy: -56.55776873 au

RMS gradient: 0.00000485 au

Point group: C3V

Optimised N-H bond distance: 1.01798 Angstrom 

Optimised H-N-H bond angle: 105.741<sup>o</sup>

<jmol><jmolApplet>
  <title> NH3</title>
  <color>black</color>
  <size>200</size>
  <uploadedFileContents>01365318_XYK17_NH3_OPTF_POP.LOG</uploadedFileContents>
</jmolApplet></jmol>



{| class="wikitable" border="1"
|+ Results
! Item !! Value !! Treshold !! Converged?
|-
| Maximum Force || 0.000004 || 0.000450 ||YES
|-
| RMS Force || 0.000004 || 0.000300 ||YES
|-
| Maximum Displacement || 0.000070 || 0.001800 ||YES
|-
| RMS Displacement || 0.000033 || 0.001200 ||YES
|}


=== Vibrations ===
[[File:01365318_XYK17_displayvibrationswindow.png]]


Expected number of vibrational modes: [3(4)-6]= 6

Degenerate modes: mode 2 and mode 3, mode 5 and mode 6

"Bending" vibrations: mode 1, mode 2 and mode 3

"Stretching" vibrations: mode 4, mode 5 and mode 6

Symmetric mode: mode 4, mode 5 and mode 6

Umbrella mode: mode 1

Expected number of bands observed an experimental spectrum: 2

=== Charge distribution ===
[[File:01365318_XYK17_chargedistribution.png]]

Charge on the N-atom: -1.125

charge on the H-atom: 0.375

These values agree with the theory, as N is more electronegative than H, therefore it tends to attract the shared pair of electrons more strongly towards itself, resulting in greater electron charge cloud which develops negative charge. 


[[Media:01365318_XYK17_NH3_OPTF_POP.LOG]]

== H<sub>2</sub> ==

Molecule: H<sub>2</sub>

Calculation method: RB3LYP

Basis set: 6-31G(d.p)

Final energy: -1.17853929 au

RMS gradient: 0.00013424 au

Point group: D<sup>*</sup>H

Optimised H-H bond distance: 0.74247 Angstrom 

Optimised H-H bond angle: 180<sup>o</sup>

<jmol><jmolApplet>
  <title> H2</title>
  <color>black</color>
  <size>200</size>
  <uploadedFileContents>01365318_XYK17_1H2_OPTF_POP.LOG</uploadedFileContents>
</jmolApplet></jmol>


{| class="wikitable" border="1"
|+ Results
! Item !! Value !! Treshold !! Converged?
|-
| Maximum Force || 0.000232 || 0.000450 ||YES
|-
| RMS Force || 0.000232 || 0.000300 ||YES
|-
| Maximum Displacement || 0.000305 || 0.001800 ||YES
|-
| RMS Displacement || 0.000431 || 0.001200 ||YES
|}

=== Vibrations ===
[[File:01365318_XYK17_displayvibrationswindow_h2.png]]

There is only one frequency, which is responsible for the "stretching" vibration of H-H bond - the stretching frequency. There's only one vibrational mode, according to [3(2)-5] = 1. It is a symmetric mode. In order for a molecule to absorb IR, its vibration must cause a net change in dipole moment of the molecule. Since the only mode is a symmetric stretch, and there's no change in dipole moment, therefore no band/peak will be observed in the IR spectrum.

=== Charge distribution ===
[[File:01365318_XYK17_chargedistribution_h2.png]]

The charges on both H atoms are zero.

This is because both atoms in the molecule are the same, therefore there's zero electronegativity difference. 


[[Media:01365318_XYK17_1H2_OPTF_POP.LOG]]


== N<sub>2</sub> ==

Molecule: N<sub>2</sub>

Calculation method: RB3LYP

Basis set: 6-31G(d.p)

Final energy: -109.52412868 au

RMS gradient: 0.00000060 au

Point group: D<sup>*</sup>H

Optimised NΞN bond distance: 1.10550 Angstrom 

Optimised NΞN bond angle: 180<sup>o</sup>

<jmol><jmolApplet>
  <title> N2</title>
  <color>black</color>
  <size>200</size>
  <uploadedFileContents>01365318_XYK17_2N2_OPTF_POP.LOG</uploadedFileContents>
</jmolApplet></jmol>


{| class="wikitable" border="1"
|+ Results
! Item !! Value !! Treshold !! Converged?
|-
| Maximum Force || 0.000001 || 0.000450 ||YES
|-
| RMS Force || 0.000001 || 0.000300 ||YES
|-
| Maximum Displacement || 0.000000 || 0.001800 ||YES
|-
| RMS Displacement || 0.000000 || 0.001200 ||YES
|}

=== Vibrations ===
[[File:01365318_XYK17_displayvibrationswindow_n2.png]]

There is only one frequency, which is responsible for the "stretching" vibration of nitrogen bond - the stretching frequency. There's only one vibrational mode, according to [3(2)-5] = 1. It is a symmetric mode. In order for a molecule to absorb IR, its vibration must cause a net change in dipole moment of the molecule. Since the only mode is a symmetric stretch and there's no change in dipole moment, therefore no band/peak will be observed in the IR spectrum.

=== Charge distribution ===
[[File:01365318_XYK17_chargedistribution_n2.png]]

The charges on both N atoms are zero.

This is because both atoms in the molecule are the same, therefore there's zero electronegativity difference. 


[[Media:01365318_XYK17_2N2_OPTF_POP.LOG]]


== Reaction energies for Haber Process ==
E(NH3)= -56.55776873 au

2*E(NH3)= -113.1155375 au

E(N2)= -109.52412868 au

E(H2)= -1.17853929 au

3*E(H2)= -3.53561787 au

ΔE=2*E(NH3)-[E(N2)+3*E(H2)]= -0.05579103 au
                           = -146.48 kJ/mol (2 dp)

The energy difference is negative. This reaction is exothermic, and heat is released. Therefore the ammonia product is more stable than the gaseous reactants.


Literature value for energy change= -92.4 kJ/mol <ref name="sourceone"/>

The difference in energy change with the experimental value might be due to the different solvent as well as the conditions of the reaction process.

== A molecule of my choice: O<sub>2</sub> ==
Molecule: O<sub>2</sub>

Calculation method: RB3LYP

Basis set: 6-31G(d.p)

Final energy: -150.25742434 au

RMS gradient: 0.00007502 au

Point group: D<sup>*</sup>H

Optimised O=O bond distance: 1.21602 Angstrom 

Optimised O=O bond angle: 180<sup>o</sup>

<jmol><jmolApplet>
  <title> O2</title>
  <color>black</color>
  <size>200</size>
  <uploadedFileContents>01365318_XYK17_O2_OPTF_POP.LOG</uploadedFileContents>
</jmolApplet></jmol>


{| class="wikitable" border="1"
|+ Results
! Item !! Value !! Treshold !! Converged?
|-
| Maximum Force || 0.000001 || 0.000450 ||YES
|-
| RMS Force || 0.000001 || 0.000300 ||YES
|-
| Maximum Displacement || 0.000000 || 0.001800 ||YES
|-
| RMS Displacement || 0.000000 || 0.001200 ||YES
|}

=== Vibrations ===
[[File:01365318_XYK17_displayvibrationswindow_o2.png]]

There is only one frequency, which is responsible for the "stretching" vibration of O=O bond - the stretching frequency. There's only one vibrational mode, according to [3(2)-5] = 1. It is a symmetric mode. In order for a molecule to absorb IR, its vibration must cause a net change in dipole moment of the molecule. Since the only mode is a symmetric stretch and there's no change in dipole moment, therefore no band/peak will be observed in the IR spectrum.

=== Charge distribution ===
[[File:01365318_XYK17_chargedistribution_o2.png]]

The charges on both O atoms are zero.

This is because both atoms in the molecule are the same, therefore there's zero electronegativity difference. 


=== Molecular orbitals ===
==== MO 1 (1st MO) ====

[[File:01365318_XYK17_o2_mo1.png]]
 
This molecular orbital(MO) which has the lowest energy, is a combination of the two 1s atomic orbitals(AOs) of each O atom. 

It is a bonding orbital. 

It is very deep in energy - -19.30736 au, which is -19.13 au much deeper than the MOs formed from the valence shell AOs. This is due to the fact that 1s atomic orbitals are smallest in size and are held very tightly to the nuclei. 

It is occupied with 2 electrons. 

Since the 1s AOs hardly overlap, the MO is not involved in bonding. 

==== MO 2 (4th MO) ====

[[File:01365318_XYK17_o2_mo2.png]]

This MO is the combination of the 2s valence AOs. 

It is an antibonding orbital. 

Its energy which is -0.79821 au is much higher than the first 2 MOs. 

It is occupied with 2 electrons. 

The AOs overlap more strongly and effectively, and since they are valence orbitals they are much more involved in chemical bonding. 

==== MO 3 (5th MO) ====

[[File:01365318_XYK17_o2_mo3.png]]

This MO is the combination of the 2p AOs. It is formed by sigma bond, which is the end-on overlap of the two p AOs along the bond.

It is a bonding orbital. 

Its energy is considerably high - -0.53151 au.

It is occupied with 2 electrons. 

The AOs overlap strongly and effectively, and since they are valence orbitals they have huge contribution to chemical bonding.

==== MO 4 (8th MO) ====

[[File:01365318_XYK17_o2_mo4.png]]

This MO is the combination of the 2p AOs. It is formed by pi bond, which is the side-by-side overlap of the two p AOs perpendicular the bond.

It is degenerate with another MO (which is the 9th MO, stated below).

It is an antibonding orbital. 

It is the HOMO. 

It is occupied.

It has huge contribution to the chemical bonding. 

==== MO 5 (9th MO) ====

[[File:01365318_XYK17_o2_mo5.png]]

This MO is the combination of the 2p AOs. It is formed by pi bond, which is the side-by-side overlap of the two p AOs perpendicular the bond.

It is degenerate with another MO (which is the 8th MO, stated above).

It is an antibonding orbital. 

It is the LUMO. 

It is unoccupied.


[[Media:01365318_XYK17_O2_OPTF_POP.LOG]]


== Independence - Second molecule of my choice: HCl ==
Molecule: HCl

Calculation method: RB3LYP

Basis set: 6-31G(d.p)

Final energy: --460.80077875 au

RMS gradient: 0.00005211 au

Point group: C<sup>*</sup>V

Optimised H-Cl bond distance: 1.28599 Angstrom 

Optimised H-Cl bond angle: 180<sup>o</sup>

<jmol><jmolApplet>
  <title>HCl</title>
  <color>black</color>
  <size>200</size>
  <uploadedFileContents>01365318_XYK17_HCL_OPTF_POP.LOG</uploadedFileContents>
</jmolApplet></jmol>


{| class="wikitable" border="1"
|+ Results
! Item !! Value !! Treshold !! Converged?
|-
| Maximum Force || 0.000090 || 0.000450 ||YES
|-
| RMS Force || 0.000090 || 0.000300 ||YES
|-
| Maximum Displacement || 0.000139 || 0.001800 ||YES
|-
| RMS Displacement || 0.000197 || 0.001200 ||YES
|}

=== Vibrations ===
[[File:01365318_XYK17_displayvibrationswindow_hydrogenchloride.png]]

There is only one frequency, which is responsible for the "stretching" vibration of H-Cl bond - the stretching frequency. There's only one vibrational mode, according to [3(2)-5] = 1. It is an asymmetric mode, due to the difference in electronegativities between H and Cl. In order for a molecule to absorb IR, its vibration must cause a net change in dipole moment of the molecule. Since the the mode is a asymmetric stretch and there's net change in dipole moment, therefore one band/peak will be observed in the IR spectrum.

=== Charge distribution ===
[[File:01365318_XYK17_chargedistribution_1hcl.png]]

Charge on the Cl-atom: -0.284

Charge on the H-atom: 0.284

These values agree with the theory, as Cl is more electronegative than H, therefore it tends to attract the shared pair of electrons more strongly towards itself, resulting in greater electron charge cloud which develops negative charge. 


[[Media:01365318_XYK17_HCL_OPTF_POP.LOG]]

== References ==
<references>

<ref name="sourceone" > AUS-e-TUTE, 14 February 2017 "Haber Process for Ammonia Production Chemistry Tutorial" Available from http://www.ausetute.com.au/haberpro.html </ref>
</references>