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Hydrogen chloride (HCl)

The linear molecule hydrogen chloride was modeled using several different levels of theory. The best ab initio level was 631-G, because it produced a model with the lowest potential energy.

plot of potential
energy of bond stretching at different levels of theory

Figure 1: The plot above describes the potential energy of bond stretching at different levels of theory.

Even though DZV had the largest basis set size, it did not produce the lowest energy solution. 631-G produced the lowest potential energy bond stretches.

Using the model produced by the 631-G theory, a display of the highest occupied molecular orbital (HOMO) was produced.

The HOMO in HCl is not involved in bonding between the atoms.

Using the model produced by the 631-G theory, a display of the lowest unoccupied molecular orbital (LUMO) was produced.

The LUMO in HCl contains no electrons, but shows which orbitals electrons can be excited and forced to enter.

The electrostatic potential describes the strength of the electric field created by the molecule. The pattern of the potential is caused by unequal sharing of electrons.

The generated image shows a larger potential surrounding the chlorine atom and a smaller potential around the hydrogen. This is expected because of chlorine's larger size.

Partial atomic charges describe the same information as the electrostatic potential.

The generated image shows chlorine is negative and hydrogen is positive. The magnitudes of the charges are equal because the molecule is neutral.

Table 1: Dipole moments at each level of theory and experimental value

Theory	Dipole Moment (uD)
Experimental	1.109
PM3	1.379
AM1	1.384
621-G	1.856
631-G	1.876
DZV	1.898

Table 2: Valence energy diagram from lowest to highest

Energy Level (hartrees)	Bonding/Antibonding	Population	Image
-104.8346	Antibonding	2
-10.576	Antibonding	2
-8.0449	Antibonding	2
-8.04	Antibonding	2
-8.04	Antibonding	2
-1.1262	Bonding	2
-0.6135	Bonding	2
-0.4791	Antibonding	2
-0.4791	Antibonding	2
0.1533	Bonding	0
0.5796	Bonding	0
0.6189	Bonding	0
0.6211	Antibonding	0
0.6211	Antibonding	0
.9856	Bonding	0

The vibrational frequency was calculated to be 2876.1404 cm^-1. The literature value was found to be 2990.95 cm^-1 (Atkins).

Based on template by A. Herráez as modified by J. Gutow

Page skeleton and JavaScript generated by export to web function using Jmol 12.2.RC3 2011-08-06 04:51 on Feb 28, 2012.

Using directory /Users/student/Desktop/HCl Website (casey hansen)/website2(HCl)
  adding JmolPopIn.js
  ...jmolApplet0
      ...adding Geometry_Optimization__G-31_.png
      ...copying
./Jmol.js
         to
/Users/student/Desktop/HCl Website (casey hansen)/website2(HCl)/Jmol.js
      ...copying
./JmolApplet.jar
         to
/Users/student/Desktop/HCl Website (casey hansen)/website2(HCl)/JmolApplet.jar
      ...copying
file:/Users/student/Desktop/HCl(caseyhansen)/HCl(geo_op631G)ch.log
         to
/Users/student/Desktop/HCl Website (casey hansen)/website2(HCl)/HCl(geo_op631G)ch.log
      ...adding Geometry_Optimization__G-31_.spt
  ...jmolApplet1
      ...adding HOMO__G-31_.png
      ...adding HOMO__G-31_.spt
  ...jmolApplet2
      ...adding LUMO__G-31_.png
      ...adding LUMO__G-31_.spt
  ...jmolApplet3
      ...adding Electrostatic_Potential__G-31_.png
      ...adding Electrostatic_Potential__G-31_.spt
  ...jmolApplet4
      ...adding Partial_Atomic_Charges__G-31_.png
      ...adding Partial_Atomic_Charges__G-31_.spt