Accuracy of Prediction of Entropy (Home)

Back to features of PM6

The entropy of gas-phase systems can be predicted using the calculated vibrational frequencies and moments of inertia and the translational contributions. For monatomic species, only translational contributions were used.  All reference data is taken from the Handbook of Chemistry and Physics.
 

Statistics for the set of 120 species

Average signed error:

  2.25 0.80*

Average unsigned error: 

  3.16 1.75*

Root mean square error:

  7.84 2.83*

*:Excluding the three worst results

Each of the PM6 results given below was generated by doing two calculations.  First, the geometry was optimized, then a THERMO calculation was done.  These calculations were done in a single run, with the data set having the form:

<keywords: none used>
<Name of species>
<Blank>
<Z-matrix: For examples, see: ref-data>
<Blank line>
 OLDGEO THERMO(298,298,0)
<Blank line>
<Blank line>

 

 

Entropies for Individual Species used in Preparing this Graph
(All values are in cal/(degree.mole))

Formula

Molecule

Ref. PM6 Diff

B5H9

Pentaborane(9)

67.07

72.63

5.56

B5H11

Pentaborane(11)

76.72

72.63

-4.09

C2H2

Acetylene

48.01

47.11

-0.90

C3H6

Cyclopropane

56.76

56.66

-0.10

C3H8

Propane

64.60

66.14

1.54

BC3H9

Trimethylborane

75.93

72.53

-3.40

C6H6

Benzene

64.34

64.61

0.27

C10H8

Naphthalene

79.61

79.29

-0.32

CNH5

Methylamine

58.05

57.51

-0.54

C2NH3

Acetonitrile

58.17

57.45

-0.72

C2NH7

Dimethylamine

65.27

64.72

-0.55

C2NH7

Ethylamine

67.83

63.50

-4.33

C3NH9

Trimethylamine

68.62

69.26

0.64

C6NH7

Aniline

75.98

73.72

-2.26

C7NH9

m-Toluidine

84.25

80.83

-3.42

C7NH9

o-Toluidine

83.89

79.43

-4.46

C7NH9

p-Toluidine

82.93

80.05

-2.88

C2N2

Cyanogen

57.82

55.69

-2.13

CH2O

Formaldehyde

52.29

52.28

-0.01

CH4O

Methanol

57.34

56.91

-0.43

C2H2O

Ketene

59.18

57.43

-1.75

C2H6O

Dimethyl ether

63.67

64.83

1.16

C2H6O

Ethanol

67.30

67.17

-0.13

C3H6O

Acetone

70.58

67.85

-2.73

C3H6O

Propanal

72.78

68.55

-4.23

C3H8O

Isopropanol

73.90

72.55

-1.35

C3H8O

Propanol

77.10

70.61

-6.49

C4H4O

Furan

63.86

64.16

0.30

C4H6O

2,3-Dihydrofuran

72.54

68.18

-4.36

C2H2O2

trans Glyoxal

65.13

65.55

0.42

C2H4O2

Acetic acid

67.76

67.64

-0.12

C2H6O2

Ethylene glycol

72.61

65.45

-7.16

C3H6O2

Methyl acetate

77.53

71.22

-6.31

CNH3O2

Nitromethane

67.61

66.66

-0.95

C2NH5O2

Nitroethane

76.60

69.25

-7.35

C6NH5O2

Nitrobenzene

83.36

81.26

-2.10

CNH3O3

Methyl nitrate

73.08

70.57

-2.51

C3NH7O3

Propyl nitrate

41.84

80.41

38.57

CN2H2O4

Dinitromethane

85.59

78.16

-7.43

CN4O8

Tetranitromethane

120.38

95.44

-24.94

C3N3H5O9

Glycerol trinitrate

130.47

94.70

-35.77

C5N4H8O12

Pentaerythritol tetranitrate

146.92

103.78

-43.14

F

Fluorine, atom

37.95

34.77

-3.18

CH3F

Fluoromethane

53.27

53.23

-0.04

C2HF

Fluoroacetylene

55.38

54.24

-1.14

C2H5F

Fluoroethane

63.21

63.00

-0.21

CNF

Cyanogen fluoride

53.70

53.02

-0.68

F2

Fluorine

48.47

48.45

-0.02

OF2

Difluorine oxide

59.15

58.85

-0.30

C2H3F3

1,1,1-Trifluoroethane

66.90

68.61

1.71

NF3

Nitrogen trifluoride

62.33

62.62

0.29

C2NF3

Trifluoroacetonitrile

71.24

71.13

-0.11

CF4

Carbon tetrafluoride

62.52

63.69

1.17

C2F6

Hexafluoroethane

79.42

76.55

-2.87

NaF

Sodium fluoride

51.72

51.98

0.26

SiCH6

Methylsilane

66.63

60.87

-5.76

SiC3H10

Trimethylsilane

79.11

77.51

-1.60

SiC4H12

Tetramethylsilane

85.80

87.40

1.60

Si2C6H18O

Hexamethyldisiloxane

127.87

108.11

-19.76

PF3

Phosphorus trifluoride

65.27

66.97

1.70

POF3

Phosphorus oxyfluoride

68.21

71.49

3.28

CH4S

Thiomethanol

60.99

59.79

-1.20

C2H6S

Thioethanol

70.79

67.38

-3.41

C3H6S

Thietane

68.12

65.96

-2.16

C4H10S

Diethyl thioether

87.98

76.18

-11.80

C2H6SO2

Dimethyl sulfone

74.24

75.28

1.04

SO2F2

Sulfuryl fluoride

67.88

71.88

4.00

CH3Cl

Methyl chloride

56.07

55.99

-0.08

C2HCl

Chloroacetylene

57.84

56.39

-1.45

C2H5Cl

Chloroethane

65.97

65.64

-0.33

CNCl

Cyanogen chloride

56.45

55.69

-0.76

ClF

Chlorine fluoride

52.08

55.69

3.61

ClF3

Chlorine trifluoride

67.30

69.34

2.04

Cl2

Chlorine

53.32

53.20

-0.12

CH2Cl2

Dichloromethane

64.58

64.52

-0.06

CCl2O

Carbonyl chloride

67.75

67.59

-0.16

SCl2O2

Sulfuryl chloride

74.55

76.05

1.50

BCl3

Boron trichloride

69.33

76.05

6.72

C2H3Cl3

1,1,1-Trichloroethane

77.22

76.47

-0.75

SiHCl3

Trichlorosilane

75.02

76.72

1.70

PCl3

Phosphorus trichloride

74.52

75.34

0.82

PCl3O

Phosphorus oxychloride

77.80

79.54

1.74

SiCl4

Silicon tetrachloride

79.04

81.52

2.48

Ar

Argon, atom

37.00

36.98

-0.02

TiCl4

Titanium tetrachloride

84.42

80.03

-4.39

CrO3

Chromium(VI) trioxide

63.62

65.20

1.58

CrCl2O2

Chromium dioxide dichloride

78.82

80.43

1.61

GeH3F

Fluorogermane

60.42

60.72

0.30

GeCl4

Germanium tetrachloride

83.10

85.48

2.38

AsH3

Arsine

53.25

53.18

-0.07

AsF3

Arsenic trifluoride

69.10

71.19

2.09

AsCl3

Arsenic trichloride

78.20

79.05

0.85

HBr

Hydrogen bromide

47.49

47.52

0.03

CH3Br

Bromomethane

58.89

58.79

-0.10

C2HBr

Bromoacetylene

60.63

58.98

-1.65

C2H5Br

Bromoethane

68.52

68.48

-0.04

CNBr

Cyanogen bromide

59.34

58.52

-0.82

NBrO

Nitrosyl bromide

65.41

64.15

-1.26

BrF

Bromine fluoride

54.73

54.60

-0.13

BrF3

Bromine trifluoride

69.91

71.01

1.10

BrF5

Bromine pentafluoride

76.53

80.18

3.65

SiH3Br

Bromosilane

62.72

63.26

0.54

BrCl

Bromine chloride

57.38

57.36

-0.02

GeH3Br

Bromogermane

65.68

66.52

0.84

Br2

Bromine

58.67

58.71

0.04

CBr2F2

Difluorodibromomethane

77.75

78.45

0.70

SiHBr3

Tribromosilane

83.30

84.85

1.55

AsBr3

Arsenic tribromide

86.97

80.02

-6.95

NbCl5

Niobium(V) pentachloride

95.75

89.63

-6.12

MoF6

Molybdenum(VI) hexafluoride

83.77

82.36

-1.41

SnCl4

Tin tetrachloride

87.42

81.36

-6.06

CH3I

Methyl iodide

60.73

60.75

0.02

C2H5I

Iodoethane

73.13

70.52

-2.61

CIF3

Trifluoroiodomethane

73.47

74.79

1.32

IBr

Iodine bromide

61.85

62.09

0.24

C2I2

Diiodoacetylene

74.83

72.09

-2.74

BI3

Boron triiodide

83.46

76.79

-6.67

CsHO

Cesium hydroxide

60.90

59.97

-0.93

WF6

Tungsten hexafluoride

81.53

80.62

-0.91

BiCl3

Bismuth trichloride

85.78

78.00

-7.78