Average Errors in DHf (Kcal.mol-1) and Bond-Lengths(Å) (Home)

Expressing average errors in heats of formation and bond-lengths is difficult, in that the averages depend on the set of compounds involved.  So in order to provide meaningful values, average errors for various sets of elements are given here. All the analyses presented here were generated using main-group raw data. and

   Core elements: H, C, N, O, only

  Heats of Formation Bond-Lengths
Element PM6 PM3 AM1 No. in set   PM6 PM3 AM1 No. in set
Hydrogen 4.6 5.5 9.3 1,126

0.021

0.017

0.037

53
Carbon 4.7 5.5 9.3 1,123

0.012

0.012

0.016

157
Nitrogen 4.4 6.0 10.1 464

0.040

0.030

0.048

51
Oxygen 4.7 5.9 9.9 627

0.028

0.026

0.054

53
Average 4.6 5.7 9.5 3,340

0.021

 0.018 0.031 314

"Organic" elements: H, C, N, O, F, P, S, Cl, Br, I, only

  Heats of Formation              Bond-Lengths
Element PM6 PM3 AM1 No. in set   PM6 PM3 AM1 No. in set
Hydrogen 4.7 6.4 9.6 1,513 0.029 0.019 0.031

93
Carbon 4.8 6.3 9.8 1,554 0.013 0.023 0.028

337
Nitrogen 4.8 6.5 10.7 542 0.035 0.032 0.046

73
Oxygen 5.2 7.9 13.3 820 0.025 0.034 0.054

130
Fluorine 6.7 12.2 26.4 176 0.034 0.028 0.043

69
Phosphorus 8.2 17.9 20.1 95 0.021 0.047 0.058

67
Sulfur 6.1 11.3 15.2 195 0.032 0.044 0.058

78
Chlorine 5.9 14.6 24.5 155 0.051 0.038 0.060

61
Bromine 5.7 9.7 18.2 58 0.034 0.111 0.077

33
Iodine 3.2 7.9 17.6 59 0.117 0.172 0.113

22
Average 5.0 7.5 12.0 5,167 0.027 0.036 0.044 963

Main-Group elements

  Heats of Formation Bond-Lengths
Element PM6 PM3 AM1 No. in set   PM6 PM3 AM1 No. in set

Hydrogen

 5.7 16.3 20.1 2,246   0.034 0.033 0.029 213

Helium

 0.0     1   0.411     5

Lithium

 7.3 18.1 17.2 83   0.149 0.163 0.157 111

Beryllium

 5.9 29.6 18.5 34   0.065 0.066 0.089 42

Boron

 8.2 12.7   118   0.033 0.067   122

Carbon

 5.6 14.4 17.9 2,038   0.031 0.049 0.060 608

Nitrogen

 6.0 18.3 23.0 714   0.084 0.120 0.153 245

Oxygen

 6.2 19.6 26.4 1,218   0.091 0.090 0.097 576

Fluorine

 7.1 19.9 35.3 344   0.065 0.067 0.092 247

Neon

 0.0     1   0.378     5

Sodium

 11.7 8.6 10.4 39   0.369 0.189 0.123 33

Magnesium

 7.9 20.0 18.7 66   0.075 0.159 0.061 106

Aluminium

 7.3 19.1 19.2 75   0.040 0.098 0.138 70

Silicon

 5.7 13.0 16.6 93   0.033 0.074 0.073 95

Phosphorus

 8.2 17.4 19.4 98   0.034 0.075 0.074 90

Sulfur

 7.4 19.1 27.0 308   0.070 0.088 0.135 184

Chlorine

 6.8 18.3 25.5 368   0.065 0.088 0.130 256

Argon

 0.0     1   0.253     4

Potassium

 6.6 9.8 42.5 42   0.125 0.142 0.239 47

Calcium

 8.9 41.9 53.3 43   0.080 0.158 0.100 72

Gallium

 7.6 47.5 46.5 47   0.048 0.195 0.144 80

Germanium

 9.7 15.8 19.1 67   0.037 0.056 0.066 133

Arsenic

 7.0 16.8 17.4 49   0.067 0.085 0.102 70

Selenium

 4.9 41.1 32.4 24   0.042 0.075 0.060 49

Bromine

 5.9 24.6 25.4 185   0.093 0.130 0.120 169

Krypton

 0.0     1   0.128     6

Rubidium

 11.0 21.6 28.1 24   0.416 0.176 0.197 36

Strontium

 7.4 76.6 57.6 38   0.085 0.085 0.200 56
Cadmium 3.4     38   0.150     57

Indium

 7.4 29.7 32.2 54   0.040 0.154 0.106 77

Tin

 6.7 16.9 21.0 78   0.072 0.077 0.082 98

Antimony

 5.4 34.7 35.1 58   0.060 0.084 0.131 90

Tellurium

 8.1 46.9 22.1 45   0.065 0.115 0.116 81

Iodine

 5.8 27.5 32.5 163   0.127 0.145 0.177 132

Xenon

 0.0     1   0.626     8

Cesium

 8.1 54.4 55.3 40   0.313 0.200 0.324 44

Barium

 11.8 129.6 145.4 37   0.146 0.183 0.202 52

Thallium

 11.3 70.8 114.7 45   0.203 0.137 0.214 60

Lead

 8.3 14.6 16.7 44   0.123 0.095 0.103 53

Bismuth

 7.8 28.9 119.7 53   0.139 0.220 0.635 81

Average

 6.2 19.1 24.1 8,983   0.080 0.097 0.116 4,506

 

All elements, except Ce, Pr, Nd, Pm Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and the elements with Z > 83,  PM6 only,

Element DHf No. in set   Bond-Length No. in set
Hydrogen

7.4

3,044

  

0.05

 240
Helium 0.0 1   0.41 5
Lithium 7.3 83   0.15 111
Beryllium 5.9 34   0.07 42
Boron 7.7 121   0.04 122
Carbon 7.5 2,806   0.05 1,193
Nitrogen 8.6 1,068   0.09 664
Oxygen 8.3 1,765   0.10 1,187
Fluorine 8.1 497   0.07 406
Neon 0.0 1   0.38 5
Sodium 11.5 40   0.37 33
Magnesium 7.9 66   0.08 106
Aluminium 7.0 75   0.05 77
Silicon 5.5 98   0.04 102
Phosphorus 8.2 110   0.04 146
Sulfur 9.0 428   0.09 365
Chlorine 8.7 671   0.08