Part 1

Optimisation of BH₃ molecule

Starting BH₃ molecule, which was created using GaussView 5.0.9, had B-H bond length of 1.5Å. Optimisation was done for the molecule based on Density Function Theory, using B3LYP method and 3-21G basis set.

Summarised Results for Optimised BH₃ Molecule

File Type: .log
Calculation Type: FOPT
Calculation Method: RB3LYP
Basis Set: 3-21G
Charge: 0
Spin: Singlet
E(RB3LYP): -26.46226338 a.u.
RMS Gradient Norm: 0.00020672 a.u.
Dipole Moment: 0.0000 Debye
Point Group: D_3h
B-H Bond Length: 1.19349Å
H-B-H Bond Angle: 120.000^o
Job CPU Time: 15.0sec

File:BH3 opt 321G JQ411.log

 Item               Value     Threshold  Converged?
 Maximum Force            0.000413     0.000450     YES
 RMS     Force            0.000271     0.000300     YES
 Maximum Displacement     0.001610     0.001800     YES
 RMS     Displacement     0.001054     0.001200     YES
 Predicted change in Energy=-1.071764D-06
 Optimization completed.
    -- Stationary point found.
                           ----------------------------
                           !   Optimized Parameters   !
                           ! (Angstroms and Degrees)  !
 --------------------------                            --------------------------
 ! Name  Definition              Value          Derivative Info.                !
 --------------------------------------------------------------------------------
 ! R1    R(1,2)                  1.1935         -DE/DX =    0.0004              !
 ! R2    R(1,3)                  1.1935         -DE/DX =    0.0004              !
 ! R3    R(1,4)                  1.1935         -DE/DX =    0.0004              !
 ! A1    A(2,1,3)              120.0            -DE/DX =    0.0                 !
 ! A2    A(2,1,4)              120.0            -DE/DX =    0.0                 !
 ! A3    A(3,1,4)              120.0            -DE/DX =    0.0                 !
 ! D1    D(2,1,4,3)            180.0            -DE/DX =    0.0                 !
 --------------------------------------------------------------------------------
 GradGradGradGradGradGradGradGradGradGradGradGradGradGradGradGradGradGrad

When the bh3_opt.log file was openedwith the 'Read Intermediate Geometry' box ticked, the starting molecule with bond length 1.5Å showed up. Options were available to view the molecule at each of the 4 optimisation step. If the mentioned box was unticked when opening the file, the options are unavailable and the Optimisation option under the Results tab was unavailable.
The results obtained from the Optimisation options was attached below. Both the Total Energy and RMS Gradient decreases through the optimisation process and reached a minimum at the final step. This shows that the final molecule had the lowest energy and is the most stable. The gradient, dE/dr, represent the force acting on the molecule. The final value of the gradient was close to zero, which indicated that there is close to zero force acting on the optimised molecule. However, the non-zero gradient at the last optimisation step indicated that the optimized molecule was not yet at equilibrium. Therefore, the optimisation has produced BH₃ molecule very closed to the equilibrium with minimum energy and close-to-zero net force acting on it.

# Total Energy
# X-Axis:  Optimization Step Number
# Y-Axis:  Total Energy (Hartree)
#                  X                   Y
        1.0000000000      -26.3829691154
        2.0000000000      -26.4176728330
        3.0000000000      -26.4610352782
        4.0000000000      -26.4622633796


# RMS Gradient Norm
# X-Axis:  Optimization Step Number
# Y-Axis:  RMS Gradient Norm (Hartree/Bohr)
#                  X                   Y
        1.0000000000        0.0355181840
        2.0000000000        0.0307318750
        3.0000000000        0.0068842700
        4.0000000000        0.0002067170

Optimisation of BH₃ using 6-21G (d,p) Basis Set

Optimisation of the BH₃ molecule obtained from stage 1 using 3-21G basis set was repeated using an improved basis set, 6-21G (d,p). Optimisation was completed in 4 steps and the results are summarized below.

Summarised Results for Optimised BH₃ Molecule

File Type: .log
Calculation Type: FOPT
Calculation Method: RB3LYP
Basis Set: 6-31G(d,p)
Charge: 0
Spin: Singlet
E(RB3LYP): -26.61532363 a.u.
RMS Gradient Norm: 0.00000296 a.u.
Dipole Moment: 0.0000 Debye
Point Group: D_3h
B-H Bond Length: 1.19232Å
H-B-H Bond Angle: 120.000^o
Job CPU Time: 5.0sec

File:BH3 opt 631G dp JQ411.log

 Item               Value     Threshold  Converged?
 Maximum Force            0.000006     0.000450     YES
 RMS     Force            0.000004     0.000300     YES
 Maximum Displacement     0.000023     0.001800     YES
 RMS     Displacement     0.000015     0.001200     YES
 Predicted change in Energy=-2.008855D-10
 Optimization completed.
    -- Stationary point found.
                           ----------------------------
                           !   Optimized Parameters   !
                           ! (Angstroms and Degrees)  !
 --------------------------                            --------------------------
 ! Name  Definition              Value          Derivative Info.                !
 --------------------------------------------------------------------------------
 ! R1    R(1,2)                  1.1923         -DE/DX =    0.0                 !
 ! R2    R(1,3)                  1.1923         -DE/DX =    0.0                 !
 ! R3    R(1,4)                  1.1923         -DE/DX =    0.0                 !
 ! A1    A(2,1,3)              120.0            -DE/DX =    0.0                 !
 ! A2    A(2,1,4)              120.0            -DE/DX =    0.0                 !
 ! A3    A(3,1,4)              120.0            -DE/DX =    0.0                 !
 ! D1    D(2,1,4,3)            180.0            -DE/DX =    0.0                 !
 --------------------------------------------------------------------------------
 GradGradGradGradGradGradGradGradGradGradGradGradGradGradGradGradGradGrad

(edit)
In comparison to the previous calculation done using 3-21G basis set, there was a slight decrease of 0.0021Å in bond length. The total energy of the molecule optimised using 6-31G(d,p) basis set was significantly lower, 0.15305914 a.u. (401.9kJ/mol), than that using 3-21G basis set. This indicated that the use of an improved basis set produced a much more stable BH₃ molecule. Like the previous result, the RMS gradient obtained remained small but non-zero. Hence, the molecule obtained is close to but not the most stable form at equilibrium.

Optimisation of TlBr₃ using PP

(raw data only)

File Type: .log
Calculation Type: FOPT
Calculation Method: RB3LYP
Basis Set: LANL2DZ
Charge: 0
Spin: Singlet
E(RB3LYP): -91.21812851 a.u.
RMS Gradient Norm: 0.00000090 a.u.
Dipole Moment: 0.0000 Debye
Point Group: D_3h
Tl-Br Bond Length: 2.65095Å
Br--Tl-Br Bond Angle: 120.000^o
Job CPU Time: 37.5sec

File:TlBr3 opt lanl2dz JQ411.log

  Item               Value     Threshold  Converged?
 Maximum Force            0.000002     0.000450     YES
 RMS     Force            0.000001     0.000300     YES
 Maximum Displacement     0.000022     0.001800     YES
 RMS     Displacement     0.000014     0.001200     YES
 Predicted change in Energy=-6.083976D-11
 Optimization completed.
    -- Stationary point found.
                           ----------------------------
                           !   Optimized Parameters   !
                           ! (Angstroms and Degrees)  !
 --------------------------                            --------------------------
 ! Name  Definition              Value          Derivative Info.                !
 --------------------------------------------------------------------------------
 ! R1    R(1,2)                  2.651          -DE/DX =    0.0                 !
 ! R2    R(1,3)                  2.651          -DE/DX =    0.0                 !
 ! R3    R(1,4)                  2.651          -DE/DX =    0.0                 !
 ! A1    A(2,1,3)              120.0            -DE/DX =    0.0                 !
 ! A2    A(2,1,4)              120.0            -DE/DX =    0.0                 !
 ! A3    A(3,1,4)              120.0            -DE/DX =    0.0                 !
 ! D1    D(2,1,4,3)            180.0            -DE/DX =    0.0                 !
 --------------------------------------------------------------------------------
 GradGradGradGradGradGradGradGradGradGradGradGradGradGradGradGradGradGrad

Optimisation of BBr₃ using PP and Basis Set

(to edit)

File Type: .log
Calculation Type: FOPT
Calculation Method: RB3LYP
Basis Set: Gen
Charge: 0
Spin: Singlet
E(RB3LYP): -64.43645296 a.u.
RMS Gradient Norm: 0.00000382 a.u.
Dipole Moment: 0.0000 Debye
Point Group: D_3h
B-Br Bond Length: 1.93396Å
Br-B-Br Bond Angle: 120.000^o
Job CPU Time: 36.7sec

File:BBr3 opt gen JQ411.log

 Item               Value     Threshold  Converged?
 Maximum Force            0.000008     0.000450     YES
 RMS     Force            0.000005     0.000300     YES
 Maximum Displacement     0.000036     0.001800     YES
 RMS     Displacement     0.000023     0.001200     YES
 Predicted change in Energy=-4.026780D-10
 Optimization completed.
    -- Stationary point found.
                           ----------------------------
                           !   Optimized Parameters   !
                           ! (Angstroms and Degrees)  !
 --------------------------                            --------------------------
 ! Name  Definition              Value          Derivative Info.                !
 --------------------------------------------------------------------------------
 ! R1    R(1,2)                  1.934          -DE/DX =    0.0                 !
 ! R2    R(1,3)                  1.934          -DE/DX =    0.0                 !
 ! R3    R(1,4)                  1.934          -DE/DX =    0.0                 !
 ! A1    A(2,1,3)              120.0            -DE/DX =    0.0                 !
 ! A2    A(2,1,4)              120.0            -DE/DX =    0.0                 !
 ! A3    A(3,1,4)              120.0            -DE/DX =    0.0                 !
 ! D1    D(2,1,4,3)            180.0            -DE/DX =    0.0                 !
 --------------------------------------------------------------------------------
 GradGradGradGradGradGradGradGradGradGradGradGradGradGradGradGrad

Optimisation of D₃h molecule - Summary of Results and Discussion

Different methods have been enployed to optimise 3 D₃h symmetry molecules. The bond lengths of the optimised molecules are shown in the table below.

Molecule	Type of bond	Optimised bond length/Å
BH₃	B-H	1.19232
BBr₃	B-Br	1.93396
TlBr₃	Tl-Br	2.65095

Discussion:

What difference does changing the ligand have?
How are H and Br similar, how are they different?
What difference does changing the central element make?
How are B and Tl similar, how are they different?
In some structures gaussview does not draw in the bonds where we expect, does this mean there is no bond? Why?
What is a bond?

Part 2

BH₃ Frequency Analysis

Summarised Results

File:BH3 FREQ JQ411.log

 Low frequencies ---   -0.9432   -0.8611   -0.0054    5.7455   11.7246   11.7625
 Low frequencies --- 1162.9963 1213.1826 1213.1853
 Harmonic frequencies (cm**-1), IR intensities (KM/Mole), Raman scattering
 activities (A**4/AMU), depolarization ratios for plane and unpolarized
 incident light, reduced masses (AMU), force constants (mDyne/A),
 and normal coordinates:
                     1                      2                      3
                    A2"                    E'                     E'
 Frequencies --  1162.9963              1213.1826              1213.1853
 Red. masses --     1.2531                 1.1072                 1.1072
 Frc consts  --     0.9986                 0.9601                 0.9601
 IR Inten    --    92.5482                14.0551                14.0587
  Atom  AN      X      Y      Z        X      Y      Z        X      Y      Z
     1   5     0.00   0.00   0.16     0.00   0.10   0.00    -0.10   0.00   0.00
     2   1     0.00   0.00  -0.57     0.00   0.08   0.00     0.81   0.00   0.00
     3   1     0.00   0.00  -0.57     0.39  -0.59   0.00     0.14  -0.39   0.00
     4   1     0.00   0.00  -0.57    -0.39  -0.59   0.00     0.14   0.39   0.00
                     4                      5                      6
                    A1'                    E'                     E'
 Frequencies --  2582.2764              2715.4465              2715.4477
 Red. masses --     1.0078                 1.1273                 1.1273
 Frc consts  --     3.9595                 4.8977                 4.8977
 IR Inten    --     0.0000               126.3302               126.3206
  Atom  AN      X      Y      Z        X      Y      Z        X      Y      Z
     1   5     0.00   0.00   0.00     0.11   0.00   0.00     0.00   0.11   0.00
     2   1     0.00  -0.58   0.00     0.02   0.00   0.00     0.00  -0.81   0.00
     3   1     0.50   0.29   0.00    -0.60  -0.36   0.00    -0.36  -0.19   0.00
     4   1    -0.50   0.29   0.00    -0.60   0.36   0.00     0.36  -0.19   0.00

No.	Symmetry (D_3h)	Frequency/cm^-1	IR (intensity)
1	E'	1163.00	92.5482
2	A2"	1213.18	14.0551
3	E'	1213.19	14.0587
4	E'	2582.28	0.0000
5	A1'	2715.45	126.3302
6	E'	2715.45	126.3206

Description of Vibration Modes:

(insert image and description)

Computed Spectrum for BH₃ Molecule

Explain why there are less than 6 peaks on IR spectrum.

TlBr₃ Frequency Analysis

Summarized Results

File:TlBr3 FREQ JQ411.log

Low frequencies ---   -3.4213   -0.0026   -0.0004    0.0015    3.9367    3.9367
 Low frequencies ---   46.4289   46.4292   52.1449
 Harmonic frequencies (cm**-1), IR intensities (KM/Mole), Raman scattering
 activities (A**4/AMU), depolarization ratios for plane and unpolarized
 incident light, reduced masses (AMU), force constants (mDyne/A),
 and normal coordinates:
                     1                      2                      3
                    E'                     E'                     A2"
 Frequencies --    46.4289                46.4292                52.1449
 Red. masses --    88.4613                88.4613               117.7209
 Frc consts  --     0.1124                 0.1124                 0.1886
 IR Inten    --     3.6867                 3.6867                 5.8466
  Atom  AN      X      Y      Z        X      Y      Z        X      Y      Z
     1  81     0.00   0.28   0.00    -0.28   0.00   0.00     0.00   0.00   0.55
     2  35     0.00   0.26   0.00     0.74   0.00   0.00     0.00   0.00  -0.48
     3  35     0.43  -0.49   0.00    -0.01  -0.43   0.00     0.00   0.00  -0.48
     4  35    -0.43  -0.49   0.00    -0.01   0.43   0.00     0.00   0.00  -0.48
                     4                      5                      6
                    A1'                    E'                     E'
 Frequencies --   165.2685               210.6948               210.6948
 Red. masses --    78.9183               101.4032               101.4032
 Frc consts  --     1.2700                 2.6522                 2.6522
 IR Inten    --     0.0000                25.4830                25.4797
  Atom  AN      X      Y      Z        X      Y      Z        X      Y      Z
     1  81     0.00   0.00   0.00     0.42   0.00   0.00     0.00   0.42   0.00
     2  35     0.00  -0.58   0.00     0.01   0.00   0.00     0.00  -0.74   0.00
     3  35     0.50   0.29   0.00    -0.55  -0.32   0.00    -0.32  -0.18   0.00
     4  35    -0.50   0.29   0.00    -0.55   0.32   0.00     0.32  -0.18   0.00

No.	Symmetry (D_3h)	Frequency/cm^-1	IR (intensity)
1	E'	46.43	3.6867
2	E'	46.43	3.6867
3	A2"	52.14	5.8446
4	A1'	165.27	0.0000
5	E'	210.69	25.4830
6	E'	210.69	25.4797

Description of Vibration Modes

Computed Spectrum for TlBr₃ Molecule

Discussion

What does the large difference in the value of the frequencies for BH3 compared to TlBr3 indicate?
Has there been a reordering of modes?
How are these spectra similar?
For both spectra two modes lie fairly closely together, the A2 and E' modes and then the other two modes also lie fairly close together, the A1' and E' modes, but higher in energy. Why is this?
Why must you use the same method and basis set for both the optimisation and frequency analysis calculations?
What is the purpose of carrying out a frequency analysis?
What do the "Low frequencies" represent?

BH₃ MO Diagram and Calculated MO

The molecular orbital diagram for D_3h BH₃ molecule is shown below. The calculated molecular orbitals using 6-31G basis set are shown next to the respective MO on the diagram. The shape, symmetry and phase pattern of the calculated molecular orbital and the molecular orbitals constructed qualitatively using a MO diagram are very similar. However, with only a qualitative approach, the energy level of 3a₁' and 1a₂" could not be determined exactly. However, using computational calculation method, the 1a₂" MO was determined to be the HOMO. Hence the 1a₂" has a lower energy level than 3a₁' as shown below.

File:Bh3 mo diagram jq411.pdf

NBO Analysis of NH₃

Optimisation - Summarised Results

File Type: .log
Calculation Type: FOPT
Calculation Method: RB3LYP
Basis Set: 6-31G(d,p)
Charge: 0
Spin: Singlet
E(RB3LYP): -56.55776856 a.u.
RMS Gradient Norm: 0.00000885 a.u.
Dipole Moment: 1.8464 Debye
Point Group: C₁
N-H Bond Length: 1.01797Å
H-N-H Bond Angle: 105.741^o
Job CPU Time: 19.0sec

File:NH3 OPT 631G JQ411.log

   Item               Value     Threshold  Converged?
 Maximum Force            0.000024     0.000450     YES
 RMS     Force            0.000012     0.000300     YES
 Maximum Displacement     0.000079     0.001800     YES
 RMS     Displacement     0.000053     0.001200     YES
 Predicted change in Energy=-1.629725D-09
 Optimization completed.
    -- Stationary point found.
                           ----------------------------
                           !   Optimized Parameters   !
                           ! (Angstroms and Degrees)  !
 --------------------------                            --------------------------
 ! Name  Definition              Value          Derivative Info.                !
 --------------------------------------------------------------------------------
 ! R1    R(1,2)                  1.018          -DE/DX =    0.0                 !
 ! R2    R(1,3)                  1.018          -DE/DX =    0.0                 !
 ! R3    R(1,4)                  1.018          -DE/DX =    0.0                 !
 ! A1    A(2,1,3)              105.7413         -DE/DX =    0.0                 !
 ! A2    A(2,1,4)              105.7486         -DE/DX =    0.0                 !
 ! A3    A(3,1,4)              105.7479         -DE/DX =    0.0                 !
 ! D1    D(2,1,4,3)           -111.8631         -DE/DX =    0.0                 !
 --------------------------------------------------------------------------------
 GradGradGradGradGradGradGradGradGradGradGradGradGradGradGradGradGradGrad

Frequency Analysis - Summarised Results

File Type: .log
Calculation Type: FREQ
Calculation Method: RB3LYP
Basis Set: 6-31G(d,p)
Charge: 0
Spin: Singlet
E(RB3LYP): -56.55776863a.u.
RMS Gradient Norm: 0.00000281 a.u.
Dipole Moment: 1.8464 Debye
Point Group: C3V (symmetry restricted for calculation)
N-H Bond Length: 1.01797Å
H-N-H Bond Angle: 105.746^o
Job CPU Time: 8.0sec

File:NH3 FREQ JQ411.log

 Low frequencies ---  -11.6223  -11.5869   -0.0033    0.0243    0.1403   25.5604
 Low frequencies --- 1089.6629 1694.1734 1694.1737
 Harmonic frequencies (cm**-1), IR intensities (KM/Mole), Raman scattering
 activities (A**4/AMU), depolarization ratios for plane and unpolarized
 incident light, reduced masses (AMU), force constants (mDyne/A),
 and normal coordinates:
                     1                      2                      3
                    A1                      E                      E
 Frequencies --  1089.6629              1694.1733              1694.1737
 Red. masses --     1.1800                 1.0644                 1.0644
 Frc consts  --     0.8255                 1.8001                 1.8001
 IR Inten    --   145.4476                13.5570                13.5572
  Atom  AN      X      Y      Z        X      Y      Z        X      Y      Z
     1   7     0.00   0.00   0.12    -0.07   0.00   0.00     0.00   0.07   0.00
     2   1     0.00  -0.21  -0.53     0.76   0.00   0.00     0.00   0.15   0.26
     3   1     0.18   0.11  -0.53     0.08  -0.39   0.22     0.39  -0.53  -0.13
     4   1    -0.18   0.11  -0.53     0.08   0.39  -0.22    -0.39  -0.53  -0.13
                     4                      5                      6
                    A1                      E                      E
 Frequencies --  3461.0664              3589.5533              3589.5534
 Red. masses --     1.0272                 1.0883                 1.0883
 Frc consts  --     7.2500                 8.2622                 8.2622
 IR Inten    --     1.0589                 0.2701                 0.2702
  Atom  AN      X      Y      Z        X      Y      Z        X      Y      Z
     1   7     0.00   0.00  -0.04     0.00   0.08   0.00     0.08   0.00   0.00
     2   1     0.00  -0.55   0.18     0.00  -0.75   0.31     0.02   0.00   0.00
     3   1     0.47   0.27   0.18    -0.34  -0.17  -0.15    -0.56  -0.34  -0.27
     4   1    -0.47   0.27   0.18     0.34  -0.17  -0.15    -0.56   0.34   0.27

Table summarizing the vibration modes
Results of frequency analysis using restricted symmetry was used to tabulate the data below.

No.	Symmetry (C_3V)	Frequency/cm^-1	IR (intensity)
1	A1	1089.66	145.4476
2	E	1694.17	13.5570
3	E	1694.17	13.5572
4	A1	3461.07	1.0589
5	E	3589.55	0.2702
6	E	3589.55	0.2701

Description of Vibration Modes

Computed IR Spectrum

Population Analysis

File Type: .chk
Calculation Type: SP
Calculation Method: RB3LYP
Basis Set: 6-31G(d,p)
Charge: 0
Spin: Singlet
E(RB3LYP): -56.55776856 a.u.
RMS Gradient Norm: - a.u.
Dipole Moment: 1.8464 Debye
Point Group: -
N-H Bond Length: 1.01797Å
H-N-H Bond Angle: 105.741^o
Job CPU Time: -

include MO diagram and screenshots here

NBO Analysis

File Type: .log
Calculation Type: SP
Calculation Method: RB3LYP
Basis Set: 6-31G(d,p)
Charge: 0
Spin: Singlet
E(RB3LYP): -56.55776856 a.u.
RMS Gradient Norm: - a.u.
Dipole Moment: 1.8464 Debye
Point Group: C1
N-H Bond Length: 1.01797Å
H-N-H Bond Angle: 105.741^o
Job CPU Time: 4.0sec
Color Range: -1.125 to 1.125

File:NH3 NBO JQ411.log

 Natural Population
                Natural  -----------------------------------------------
    Atom  No    Charge         Core      Valence    Rydberg      Total
 -----------------------------------------------------------------------
      N    1   -1.12515      1.99982     6.11104    0.01429     8.12515
      H    2    0.37505      0.00000     0.62250    0.00246     0.62495
      H    3    0.37505      0.00000     0.62250    0.00246     0.62495
      H    4    0.37505      0.00000     0.62249    0.00246     0.62495
 =======================================================================
   * Total *    0.00000      1.99982     7.97852    0.02166    10.00000

(Occupancy)   Bond orbital/ Coefficients/ Hybrids
 ---------------------------------------------------------------------------------
     1. (1.99909) BD ( 1) N   1 - H   2 
                ( 68.83%)   0.8297* N   1 s( 24.87%)p 3.02( 75.05%)d 0.00(  0.09%)
                                           -0.0001 -0.4986 -0.0059  0.0000 -0.2910
                                            0.0052  0.8155  0.0277  0.0000  0.0000
                                            0.0281  0.0000  0.0000  0.0032  0.0082
                ( 31.17%)   0.5583* H   2 s( 99.91%)p 0.00(  0.09%)
                                           -0.9996  0.0000  0.0072 -0.0289  0.0000
     2. (1.99909) BD ( 1) N   1 - H   3 
                ( 68.83%)   0.8297* N   1 s( 24.86%)p 3.02( 75.05%)d 0.00(  0.09%)
                                            0.0001  0.4986  0.0059  0.0000  0.2910
                                           -0.0052  0.4077  0.0138  0.7062  0.0240
                                            0.0140  0.0243  0.0076  0.0033  0.0031
                ( 31.17%)   0.5583* H   3 s( 99.91%)p 0.00(  0.09%)
                                            0.9996  0.0000 -0.0072 -0.0145 -0.0250
     3. (1.99909) BD ( 1) N   1 - H   4 
                ( 68.83%)   0.8297* N   1 s( 24.87%)p 3.02( 75.05%)d 0.00(  0.09%)
                                            0.0001  0.4986  0.0059  0.0000  0.2909
                                           -0.0052  0.4077  0.0138 -0.7062 -0.0239
                                            0.0140 -0.0243 -0.0076  0.0033  0.0031
                ( 31.17%)   0.5583* H   4 s( 99.91%)p 0.00(  0.09%)
                                            0.9996  0.0000 -0.0072 -0.0145  0.0250
     4. (1.99982) CR ( 1) N   1           s(100.00%)
                                            1.0000 -0.0002  0.0000  0.0000  0.0000
                                            0.0000  0.0000  0.0000  0.0000  0.0000
                                            0.0000  0.0000  0.0000  0.0000  0.0000
     5. (1.99721) LP ( 1) N   1           s( 25.38%)p 2.94( 74.52%)d 0.00(  0.10%)
                                            0.0001  0.5036 -0.0120  0.0000 -0.8618
                                            0.0505  0.0000  0.0000  0.0000  0.0000
                                            0.0000  0.0000  0.0000 -0.0269  0.0155

  Natural Bond Orbitals (Summary):

                                                            Principal Delocalizations
           NBO                        Occupancy    Energy   (geminal,vicinal,remote)
 ====================================================================================
 Molecular unit  1  (H3N)
     1. BD (   1) N   1 - H   2          1.99909    -0.60417  
     2. BD (   1) N   1 - H   3          1.99909    -0.60417  
     3. BD (   1) N   1 - H   4          1.99909    -0.60416  
     4. CR (   1) N   1                  1.99982   -14.16768  
     5. LP (   1) N   1                  1.99721    -0.31756  24(v),16(v),20(v),17(v)
                                                    21(v),25(v)

Association Energy

Optimization and Frequency Analysis of BH3NH₃

Optimisation Summarised Results

File Type: .log
Calculation Type: FOPT
Calculation Method: RB3LYP
Basis Set: 6-31G(d,p)
Charge: 0
Spin: Singlet
E(RB3LYP): -83.22468956a.u.
RMS Gradient Norm: 0.00005843 a.u.
Dipole Moment: 5.5651 Debye
Point Group: C₁
N-B Bond Length: 1.66807Å
N-H Bond Length: 1.01860Å increase bond length
B-H Bond Length: 1.21005Å increase bond length
H-B-H Bond Angle: 113.874^o reduced bond angle (4 bond pairs present now but angle less than tetrahedral)
H-N-H Bond Angle: 107.868^o increase bond angle (reduced repulsion from bond pair in BH3NH3 than lone pair in NH3)
H-N-B Bond Angle: 111.028^o
H-B-N Bond Angle: 104.600^o 4 bond pairs around B atom, no longer planar
Dihedral Angle: 59.998^o staggered conformation reducing steric hindrance
Job CPU Time: 1min 31.0sec

File:BH3NH3 OPT 631GDP JQ411.log

Item               Value     Threshold  Converged?
 Maximum Force            0.000124     0.000450     YES
 RMS     Force            0.000057     0.000300     YES
 Maximum Displacement     0.000660     0.001800     YES
 RMS     Displacement     0.000304     0.001200     YES
 Predicted change in Energy=-1.649877D-07
 Optimization completed.
    -- Stationary point found.

Frequency Analysis Summarised Results

File Type: .log
Calculation Type: FREQ
Calculation Method: RB3LYP
Basis Set: 6-31G(d,p)
Charge: 0
Spin: Singlet
E(RB3LYP): -83.22469013a.u.
RMS Gradient Norm: 0.00006160 a.u.
Dipole Moment: 5.5648 Debye
Point Group: C_3v (restricted for frequency analysis)
N-B Bond Length: 1.66807Å
N-H Bond Length: 1.01860Å increase bond length
B-H Bond Length: 1.21005Å increase bond length
H-B-H Bond Angle: 113.877^o reduced bond angle (4 bond pairs present now but angle less than tetrahedral)
H-N-H Bond Angle: 107.872^o increase bond angle (reduced repulsion from bond pair in BH3NH3 than lone pair in NH3)
H-N-B Bond Angle: 111.027^o
H-B-N Bond Angle: 104.593^o 4 bond pairs around B atom, no longer planar
Dihedral Angle: 60^o staggered conformation reducing steric hindrance
Job CPU Time: 36.0sec

File:BH3NH3 FREQ 631GDP JQ411.log

Low frequencies ---   -0.0614   -0.0462   -0.0066   21.4199   21.4259   40.8153
 Low frequencies ---  266.0487  632.3810  640.1253

highest low frequency is ~40cm-1

Association Energy of BH3NH3

Molecule	Optimised Energy/ au
BH3	-26.61532363
NH3	-56.55776856
BH3NH3	-83.22468956

ΔE=E(NH3BH3)-[E(NH3)+E(BH3)]
ΔE=-0.05159737 au
ΔE=-135.47kJ/mol
Calculated value is about -20kJ/mol different from literature value (Constantin Z. 1981. doi: 10.1063/1.441886) calculated using different method and basis set.

Part 1

Optimisation of BH3 molecule

Summarised Results for Optimised BH3 Molecule

Optimisation of BH3 using 6-21G (d,p) Basis Set

Summarised Results for Optimised BH3 Molecule

Optimisation of TlBr3 using PP

Optimisation of BBr3 using PP and Basis Set

Optimisation of D3h molecule - Summary of Results and Discussion

Part 2

BH3 Frequency Analysis

Summarised Results

Description of Vibration Modes:

Computed Spectrum for BH3 Molecule

TlBr3 Frequency Analysis

Summarized Results

Description of Vibration Modes

Computed Spectrum for TlBr3 Molecule

Discussion

BH3 MO Diagram and Calculated MO

NBO Analysis of NH3

Optimisation - Summarised Results

Frequency Analysis - Summarised Results

Description of Vibration Modes

Computed IR Spectrum

Population Analysis

NBO Analysis

Association Energy

Optimization and Frequency Analysis of BH3NH3

Association Energy of BH3NH3

Optimisation of BH₃ molecule

Summarised Results for Optimised BH₃ Molecule

Optimisation of BH₃ using 6-21G (d,p) Basis Set

Summarised Results for Optimised BH₃ Molecule

Optimisation of TlBr₃ using PP

Optimisation of BBr₃ using PP and Basis Set

Optimisation of D₃h molecule - Summary of Results and Discussion

BH₃ Frequency Analysis

Computed Spectrum for BH₃ Molecule

TlBr₃ Frequency Analysis

Computed Spectrum for TlBr₃ Molecule

BH₃ MO Diagram and Calculated MO

NBO Analysis of NH₃

Optimization and Frequency Analysis of BH3NH₃