ChemWiki - User contributions [en]

0MW7FY8

2018-02-23T13:22:06Z

Jf1717:

Jacob Forrest

== ''Optimisation of NH3'' ==

=== Molecule - NH3 ===

'''the method''': B3LYP

'''the basis set''': 6-31G(d,p)

'''final energy E(RB3LYP) in atomic units''': -56.55776873 au

'''point group''' : C3v

'''Bond length''' : 1.01798 au

'''H-N-H bond angle''' : 105.745 degrees

<pre>

Item Value Threshold Converged?
Maximum Force 0.000006 0.000450 YES
RMS Force 0.000004 0.000300 YES
Maximum Displacement 0.000014 0.001800 YES
RMS Displacement 0.000009 0.001200 YES

</pre>

[[File:JHF_NH3_OPT.LOG]]

<jmol><jmolApplet>
<title>Ammonia</title>
<color>black</color>
<size>200</size>
<script>frame 1.16</script>
<uploadedFileContents>JHF_NH3_OPT.LOG</uploadedFileContents>
</jmolApplet></jmol>

[[File:Vibrations JHF table.jpg]]

=== NH3 bond vibrations ===

'''how many modes do you expect from the 3N-6 rule?'''

6 because NH3 has 6 modes of vibration

'''which modes are degenerate (ie have the same energy)?'''
2+3, 5+6 , They are both the two asymmetric stretches(5+6)
and bends(2+3)

'''which modes are "bending" vibrations and which are "bond stretch" vibrations?'''
1,2,3 then 4,5,6

'''which mode is highly symmetric?'''
4 because the symmetric stretches do not at all affect the shape or dipoles of the
the molecule

'''one mode is known as the "umbrella" mode, which one is this?'''
1 because the symmetric stretching animation looks similar to the opening and closing
of an umbrella

'''how many bands would you expect to see in an experimental spectrum of gaseous ammonia?'''
4 because there are 4 vibration modes that create imbalanced dipoles (2,3,5,6)

=== Charge distribution in NH3 ===

It is expected for the Nitrogen to have a negative
charge as it is more electronegative than hydrogen and
therefore will draw the majority of electron density of
the molecule to itself this in turn means the hydrogen is
expected to be positive and for all of the hydrogen atoms
to have the same magnitude of charge as they are all equally
electronegative and equally distanced from the nitrogen atom.

'''Nitrogen charge''' = -1.125

'''Hydrogen charge''' = 0.375

=== Molecule - N2 ===

'''Molecule''' : N2

'''the method''': B3LYP

'''the basis set''': 6-31G(d,p)

'''final energy E(RB3LYP) in atomic units''': -109.52412868 au

'''point group''' : D∞h

'''Bond length''' : 1.10550 A

[[File:N2_OPTIMISATION.LOG]]

Item Value Threshold 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''' - #Mode:1 // Freq: 2457.33cm-1

=== Molecule - H2 ===

'''Molecule''' : H2

'''the method''': B3LYP

'''the basis set''': 6-31G(d,p)

'''final energy E(RB3LYP) in atomic units''': -1.17835689 au

'''point group''' : D∞h

'''Bond length''' : 0.74279 A

[[File:H2_OPTIMISATION.LOG]]

Item Value Threshold Converged?
Maximum Force 0.000000 0.000450 YES
RMS Force 0.000000 0.000300 YES
Maximum Displacement 0.000000 0.001800 YES
RMS Displacement 0.000001 0.001200 YES

'''Vibrations''' - #Mode:1 // Freq: 4465.68cm-1

=== Reaction energy of Haber-Bosch process ===

E(NH3)= -56.55776873 au
2*E(NH3)= -113.11553746 au
E(N2)= -109.52412868 au
E(H2)= -1.17835689 au
3*E(H2)= -3.53507067 au
ΔE=2*E(NH3)-[E(N2)+3*E(H2)]= -0.05633811 au
Therefore in kj/mol = -147.92 (2 d.p)
So the ammonia product is more stable as the forming of the ammonia releases more energy than the separation of the N2 amd H2 molecules; the reaction is exothermic. However this does not mean that N-H bonds individually more stable than the reactants but the overall energy and proportionally the stability of the N-H bonds formed is greater than the energy required to break the N2 and H2 bonds for the formation of the ammonia.

== ClF3 optimisation ==

=== Vibrations and charges ===

'''mode''' '''freq(cm-1)'''
1 -43.17
2 -43.16
3 416.55
4 559.35
5 610.87
6 610.87

'''Fluorine charge''' = -0.396
'''Chlorine charge''' = 1.188

0MW7FY8

2018-02-23T13:18:16Z

Jf1717: /* Vibrations and charges */

== ''Optimisation of NH3'' ==

=== Molecule - NH3 ===

'''the method''': B3LYP

'''the basis set''': 6-31G(d,p)

'''final energy E(RB3LYP) in atomic units''': -56.55776873 au

'''point group''' : C3v

'''Bond length''' : 1.01798 au

'''H-N-H bond angle''' : 105.745 degrees

<pre>

Item Value Threshold Converged?
Maximum Force 0.000006 0.000450 YES
RMS Force 0.000004 0.000300 YES
Maximum Displacement 0.000014 0.001800 YES
RMS Displacement 0.000009 0.001200 YES

</pre>

[[File:JHF_NH3_OPT.LOG]]

<jmol><jmolApplet>
<title>Ammonia</title>
<color>black</color>
<size>200</size>
<script>frame 1.16</script>
<uploadedFileContents>JHF_NH3_OPT.LOG</uploadedFileContents>
</jmolApplet></jmol>

[[File:Vibrations JHF table.jpg]]

=== NH3 bond vibrations ===

'''how many modes do you expect from the 3N-6 rule?'''

6 because NH3 has 6 modes of vibration

'''which modes are degenerate (ie have the same energy)?'''
2+3, 5+6 , They are both the two asymmetric stretches(5+6)
and bends(2+3)

'''which modes are "bending" vibrations and which are "bond stretch" vibrations?'''
1,2,3 then 4,5,6

'''which mode is highly symmetric?'''
4 because the symmetric stretches do not at all affect the shape or dipoles of the
the molecule

'''one mode is known as the "umbrella" mode, which one is this?'''
1 because the symmetric stretching animation looks similar to the opening and closing
of an umbrella

'''how many bands would you expect to see in an experimental spectrum of gaseous ammonia?'''
4 because there are 4 vibration modes that create imbalanced dipoles (2,3,5,6)

=== Charge distribution in NH3 ===

It is expected for the Nitrogen to have a negative
charge as it is more electronegative than hydrogen and
therefore will draw the majority of electron density of
the molecule to itself this in turn means the hydrogen is
expected to be positive and for all of the hydrogen atoms
to have the same magnitude of charge as they are all equally
electronegative and equally distanced from the nitrogen atom.

'''Nitrogen charge''' = -1.125

'''Hydrogen charge''' = 0.375

=== Molecule - N2 ===

'''Molecule''' : N2

'''the method''': B3LYP

'''the basis set''': 6-31G(d,p)

'''final energy E(RB3LYP) in atomic units''': -109.52412868 au

'''point group''' : D∞h

'''Bond length''' : 1.10550 A

[[File:N2_OPTIMISATION.LOG]]

Item Value Threshold 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''' - #Mode:1 // Freq: 2457.33cm-1

=== Molecule - H2 ===

'''Molecule''' : H2

'''the method''': B3LYP

'''the basis set''': 6-31G(d,p)

'''final energy E(RB3LYP) in atomic units''': -1.17835689 au

'''point group''' : D∞h

'''Bond length''' : 0.74279 A

[[File:H2_OPTIMISATION.LOG]]

Item Value Threshold Converged?
Maximum Force 0.000000 0.000450 YES
RMS Force 0.000000 0.000300 YES
Maximum Displacement 0.000000 0.001800 YES
RMS Displacement 0.000001 0.001200 YES

'''Vibrations''' - #Mode:1 // Freq: 4465.68cm-1

=== Reaction energy of Haber-Bosch process ===

E(NH3)= -56.55776873 au
2*E(NH3)= -113.11553746 au
E(N2)= -109.52412868 au
E(H2)= -1.17835689 au
3*E(H2)= -3.53507067 au
ΔE=2*E(NH3)-[E(N2)+3*E(H2)]= -0.05633811 au
Therefore in kj/mol = -147.92 (2 d.p)
So the ammonia product is more stable as the forming of the ammonia releases more energy than the separation of the N2 amd H2 molecules; the reaction is exothermic. However this does not mean that N-H bonds individually more stable than the reactants but the overall energy and proportionally the stability of the N-H bonds formed is greater than the energy required to break the N2 and H2 bonds for the formation of the ammonia.

== ClF3 optimisation ==

=== Vibrations and charges ===

'''mode''' '''freq(cm-1)'''
1 -43.17
2 -43.16
3 416.55
4 559.35
5 610.87
6 610.87

'''Fluorine charge''' = -0.396
'''Chlorine charge''' = 1.188

0MW7FY8

2018-02-23T13:15:38Z

2018-02-19T11:33:14Z

Jf1717: Jf1717 uploaded File:Vibrations table.png

#REDIRECT [[File:Psl vibrations table.png]]

0MW7FY8

2018-02-19T11:32:41Z

Jf1717: /* Optimisation of NH3 */

0MW7FY8

2018-02-19T11:30:43Z

Jf1717: /* Optimisation of NH3 */

0MW7FY8

2018-02-19T11:30:09Z

Jf1717: /* Optimisation of NH3 */

0MW7FY8

2018-02-19T11:28:37Z

Jf1717: /* Optimisation of NH3 */