Computational Chemistry

Moments, Charges, Bond Orders, Atoms-in-Molecules......... 7.3.4 Properties Arising from Electron Distribution – Dipole

Moments, Charges, Bond Orders, Atoms-in-Molecules

The theory behind calculating dipole moments, charges, and bond orders, and using
atoms-in-molecules analyses, was outlined in Section 5.5.4; here the results of
applying DFT calculations to these will be presented.

7.3.4.1 Dipole Moments

Hehre [ 67 ] and Hehre and Lou [ 68 ] have provided quite extensive compilations of
calculated dipole moments. These confirm that Hartree–Fock dipole moments tend

80

60

40

20

0

TR_TNTRNS

TR_TNTRNS

0

26

52

78

4000

4000

3000

3500 3000

2000

2500 2000

1000

1500 1000 500

Benzene^3091

Experimental

B3LYP / 6-31G*

MP2 / 6-31G*

3050

1480

1040

674

692

1083

1540

689

1533 1071

3201

3239

FREQ_VAL

FREQ_VAL

0

37

73

1.1e+002

4000 3500 3000 2500 2000 1500 1000 500

Fig. 7.5 Experimental (gas phase), DFT (B3LYP/6-31G) and ab initio (MP2(fc)/6-31G)
calculated IR spectra of benzene

7.3 Applications of Density Functional Theory 487