Table 2. Fit of QMPFF to QM for various types of data in training set.

	Number of cases	rms error	Percent error
Property fitted			QMPFF	MMFF
Polarizability, Å3	132	0.44	2.7	—
Dipole moment, Debye	110	0.29	12.5	30.0
Quadrupole moment, Buckingham	128	2.20	11.9	30.0
Random dimer energies, kcal/mol	5,093	0.27	22.0	44.0
Optimized dimer energies, kcal/mol	81	0.95	13.7	18.7
Optimized dimer geometry, Å	81	0.10	3.3	5.0

Detailed data on molecular properties of dimers are given in Tables 5-7.