Range of Applicability of Computational Methods

Computational
Method Elements (Z) Molecular
Size

Molecular Mechanics
(MM2, MMX) 1-17, 35, 53 10,000 Atoms

Semi-Empirical
(AM1, PM3) 1-17, 35^# 300 Atoms

Ab Initio (all)^$ 1-54 (3-21G*), 1-36 (6-31G*) 200 Atoms
2000 basis functions

Density Functional 1-54 200 atoms
2000 basis functions

Ab Initio (MP2) 1-17 200 atoms
2000 basis functions

Computational Method	Elements (Z)	Molecular Size
Molecular Mechanics (MM2, MMX)	1-17, 35, 53	10,000 Atoms
Semi-Empirical (AM1, PM3)	1-17, 35^#	300 Atoms
Ab Initio (all)^$	1-54 (3-21G), 1-36 (6-31G)	200 Atoms 2000 basis functions
Density Functional	1-54	200 atoms 2000 basis functions
Ab Initio (MP2)	1-17	200 atoms 2000 basis functions

^#No d orbitals, elements 11-17, 35 in AM1; PM3(tm) as implemented in Spartan includes new parameters for transition metals, but not explicit d orbitals.

^$ Applicability of ab initio methods can be extended by the use of ecp's (effective core potentials) or pseudopotentials; however, these also are not yet widely available.

This page last modified 9:48 AM on Monday November 3rd, 2003.
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