Accuracy of Prediction of Polarizability (home)

By use of a keywords "POLAR" and "STATIC" the polarizability of a molecule can be calculated.  For a set of 77 neutral molecules, the average unsigned error was 2.1%.

"STATIC" uses a set of applied electric fields to evaluate the effect on the calculated heat of formation and on the dipole.  From the resulting three by three tensor, the polarizability along three orthogonal axes can be evaluated.  A measure of the precision of the calculation can be obtained by comparing the polarizability calculated by the two methods.

"POLAR" evaluates the frequency dependent response of a molecule.  The response can be expressed as the series expansion: Charge, dipole, polarizability (alpha), beta and gamma (the first and second hyperpolarizabilities)

The calculated polarizability is modified to include atomic correction terms.  Given a calculated polarizability of "R", the corrected polarizability is give as:

Polarizability = 0.262114*H+0.485071*C+0.154301*O+0.204743*N+1.45331*S+0.199611*F+1.23621*Cl+2.14242*Br+3.82316*I+2.31461*P+1.88611*Si+0.791396*R+0.373638

where "H", "C", etc. are the number of hydrogen, carbon, etc. atoms in the molecule.

For the 77 compounds used, the value of   R2 is 0.9942 and the cross-validated R2 is 0.9901.

Individual Species used in Preparing this Graph
(in order of increasing polarizability)

Chemical

Exp. alpha PM6 P-C Abs(PM6-Exp)

Fluoromethane

 2.590 2.878 0.288 0.288

Methane

 2.600 2.672 0.072 0.072

Acetylene

 3.330 3.322 -0.008 0.008

Formic acid

 3.400 3.438 0.038 0.038

Formamide

 4.200 4.076 -0.124 0.124

Ethylene

 4.250 4.119 -0.131 0.131

Acetonitrile

 4.400 4.440 0.040 0.040

Fluoroethane

 4.430 4.698 0.268 0.268

Ethane

 4.470 4.481 0.011 0.011

Methyl chloride

 4.530 4.339 -0.191 0.191

Acetaldehyde

 4.570 4.579 0.009 0.009

Sulfur trioxide

 4.840 4.841 0.001 0.001

Phosphine

 4.840 4.909 0.069 0.069

Ethanol

 5.110 5.063 -0.047 0.047

Acetic acid

 5.130 5.247 0.117 0.117

Silane

 5.440 5.419 -0.021 0.021

SiF4

 5.450 5.624 0.174 0.174

Dimethylamine

 5.650 5.697 0.047 0.047

Ethylamine

 5.870 5.616 -0.254 0.254

Phosphorus pentafluoride

 6.100 5.981 -0.119 0.119

Propane

 6.290 6.276 -0.014 0.014

Acetone

 6.330 6.393 0.063 0.063

Chloroethane

 6.410 6.260 -0.150 0.150

Dichloromethane

 6.480 6.264 -0.216 0.216

Sulfur hexafluoride

 6.540 6.077 -0.463 0.463

Fluorodichloromethane

 6.610 6.667 0.057 0.057

Acetyl chloride

 6.670 6.728 0.058 0.058

Bromochlorofluoromethane

 7.390 7.896 0.506 0.506

Thioethanol

 7.410 7.515 0.105 0.105

Bromoethane

 7.540 7.446 -0.094 0.094

Bromochloromethane

 7.580 7.428 -0.152 0.152

Fluoroiodomethane

 7.760 7.925 0.165 0.165

Trimethylamine

 7.770 7.591 -0.179 0.179

Acetyl bromide

 7.940 8.077 0.137 0.137

alpha-Bromoacetic acid

 8.100 8.147 0.047 0.047

n-Butane

 8.200 8.083 -0.117 0.117

Chloroform

 8.510 8.409 -0.101 0.101

Dibromomethane

 8.690 8.473 -0.217 0.217

Dibromofluoromethane

 8.740 9.011 0.271 0.271

Acetic anhydride

 8.870 9.324 0.454 0.454

1,1-Dichloro-1,2,2,2-tetrafluoroethane

 8.950 9.231 0.281 0.281

1-Bromo-2-chloroethane

 9.460 9.416 -0.044 0.044

Pyridine

 9.540 9.380 -0.160 0.160

Bromodichloromethane

 9.590 9.644 0.054 0.054

Diethyl ketone

 9.590 10.060 0.470 0.470

Chloroiodomethane

 9.640 9.696 0.056 0.056

Diethylamine

 9.660 9.352 -0.308 0.308

Thiophene

 9.670 10.118 0.448 0.448

Benzene

 10.330 10.167 -0.163 0.163

Acetyl iodide

 10.370 10.486 0.116 0.116

Carbon tetrachloride

 10.480 10.668 0.188 0.188

2,2,2-Trichloroacetaldehyde

 10.500 10.619 0.119 0.119

SO2Cl2

 10.500 9.726 -0.774 0.774

Dibromochloromethane

 10.710 10.760 0.050 0.050

Bromoiodomethane

 10.790 10.683 -0.107 0.107

Diethyl thioether

 10.800 11.433 0.633 0.633

1,1-Dibromoethane

 10.890 10.620 -0.270 0.270

Trichloroacetic acid

 10.960 10.619 -0.341 0.341

Disilane

 11.100 11.024 -0.076 0.076

Cyclohexanol (eq)

 11.560 11.727 0.167 0.167

Trichlorobromomethane

 11.610 11.987 0.377 0.377

n-Hexane

 11.760 11.717 -0.043 0.043

Bromoform

 11.820 11.760 -0.060 0.060

Aniline

 12.070 11.835 -0.235 0.235

Toluene

 12.310 12.133 -0.177 0.177

Phosphorus trichloride

 12.800 12.850 0.050 0.050

Benzaldehyde

 12.800 12.577 -0.223 0.223

Diiodomethane

 12.910 12.794 -0.116 0.116

Phenylhydrazine

 12.910 13.185 0.275 0.275

Anisole

 12.980 13.130 0.150 0.150

m-Cresol

 13.050 12.999 -0.051 0.051

n-Heptane

 13.610 13.540 -0.070 0.070

2,2,2-Tribromoacetaldehyde

 14.170 14.099 -0.071 0.071

Styrene

 14.450 13.936 -0.514 0.514

Acetophenone

 15.000 14.346 -0.654 0.654

Quinoline

 15.700 16.406 0.706 0.706

Isoquinoline

 16.430 16.348

-0.082

 0.082

Totals

 672.500 14.274