Performance of Methods

Performance of Computational Methods

Computational
Method DH_f
or total energy Bond Length Bond Angle Dihedral
Angle Dipole IP

Molecular Mechanics
(MM3, MMX) 0.5 kcal/mol 0.01 Å 1.0° 8.0° 0.1 D NA

Semi-Empirical^#
(AM1, PM3) 8 kcal/mol 0.048 Å 3.8° poor 0.6 D 0.7 eV

HF/STO-3G 90 kcal/mol (TE) 0.06 Å 1.7° --- 0.5 D ---

HF/3-21G* 58 kcal/mol (TE) 0.03 Å 1.7° --- 0.4 D ---

HF/6-31G* DH_f (isodesmic) 4kcal/mol
or 51 kcal/mol (TE) 0.032 Å 1.4° --- 0.2 D ---

B3LYP/6-31G* 7.9 kcal/mol (TE) 0.02 Å 1.4° --- 0.2 D 0.2 eV

HF/6-31G*/MP2 11.2 kcal/mol (TE) 0.048 Å 1.5#176; --- --- ---

Computational Method	DH_f or total energy	Bond Length	Bond Angle	Dihedral Angle	Dipole	IP
Molecular Mechanics (MM3, MMX)	0.5 kcal/mol	0.01 Å	1.0°	8.0°	0.1 D	NA
Semi-Empirical^# (AM1, PM3)	8 kcal/mol	0.048 Å	3.8°	poor	0.6 D	0.7 eV
HF/STO-3G	90 kcal/mol (TE)	0.06 Å	1.7°	---	0.5 D	---
HF/3-21G*	58 kcal/mol (TE)	0.03 Å	1.7°	---	0.4 D	---
HF/6-31G*	DH_f (isodesmic) 4kcal/mol or 51 kcal/mol (TE)	0.032 Å	1.4°	---	0.2 D	---
B3LYP/6-31G*	7.9 kcal/mol (TE)	0.02 Å	1.4°	---	0.2 D	0.2 eV
HF/6-31G*/MP2	11.2 kcal/mol (TE)	0.048 Å	1.5#176;	---	---	---

^#Semi-empirical methods perform better the closer in structure one gets to the "training set" of molecules that was used to parameterize them.

Data in the TAble are based on (1) Hehre, Radom, Schleyer, and Pople, Ab Initio Molecular Orbital Theory, Wiley, New York, 1986; and (2) Young, Computational Chemistry, Wiley, New York, 2001.

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