Heats of formation and strain energies for [CH]8isomers calculated by all-valence-electron semi-empirical SCF–MO theories

1971 ◽  
Vol 0 (21) ◽  
pp. 1408-1409 ◽  
Author(s):  
Hiizu Iwamura ◽  
Kazuhiko Morio ◽  
Tosiyasu L. Kunii
Keyword(s):  
Valence Electron ◽  
Heats Of Formation ◽  
Semi Empirical

scholarly journals An Improved Semi-Empirical SCF MO Method for Valence Electron Systems

1967 ◽  
Vol 40 (4) ◽  
pp. 1017-1017 ◽  
Author(s):  
Hiroshi Kato ◽  
Hideyuki Konishi ◽  
Teijiro Yonezawa
Keyword(s):  
Valence Electron ◽  
Electron Systems ◽  
Semi Empirical

Semi-empirical all-valence-electron SCF calculations of acidities of cycloalkanes

1970 ◽  
Vol 17 (3) ◽  
pp. 165-170 ◽  
Author(s):  
Raymond G. Jesaitis ◽  
Andrew Streitwieser
Keyword(s):  
Valence Electron ◽  
Semi Empirical ◽  
Scf Calculations

scholarly journals A Comparison of the Accuracy of Semi-empirical PM3, PDDG and PM6 methods in Predicting Heats of Formation for Organic Compounds

2017 ◽  
Vol 58 (2) ◽  
Author(s):  
Yang-Yang Wu ◽  
Feng-Qi Zhao ◽  
Xue-Hai Ju
Keyword(s):  
Organic Compounds ◽  
Least Square Method ◽  
Least Square ◽  
Heats Of Formation ◽  
Regression Equations ◽  
Chemical Calculation ◽  
Average Deviation ◽  
Experimental Values ◽  
Isomerization Energy ◽  
Semi Empirical

<p>Gas phase heats of formation (HOF) of 18 kinds of 390 organic compounds were calculated by quantum chemical calculation using semi-empirical PM3, PDDG and PM6 methods. The calculated HOFs were compared with the experimental data to illustrate the accuracy for different kinds of organics. Furthermore, the calculated values were linearly fitted with experimental values using the least square method, and were afterward substituted into the fitted regression equations to obtain the calibrated ones. The results show that, for 10 kinds of the selected organics, PM6 is more accurate, and PDDG is more accurate for 7 kinds of organics, while PM3 is only good for amino acid. As a whole, PM6 predicts the HOFs more accurately, with its weighted total mean average deviation (WTMAD) being 0.4 kJ/mol and 2.4 kJ/mol smaller than those of PM3 and PDDG, respectively. On the other hand, our results show that PDDG is the best to differentiate the isomers, with its mean average deviation (MAD) for isomerization energy being 7.8 kJ/mol and 11.0 kJ/mol smaller than PM6 and PM3, respectively. After the calibration, the values of MADs from the PM3, PDDG and PM6 results for most organics are reduced by 0.1 to 18.2 kJ/mol, with exceptions of the PM3 for amines, PDDG for carboxylic acids, and PM6 for ethers.</p>

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