MOPAC 2002 v2.3

Addition of AM1-d:
New AM1 parameters available for V and Pd. These elements use a s-p-d basis set. The full set of metals that can be run using AM1 is now V, Fe, Cu, Mo, Pd, Ag, and Pt.

Linear scaling COSMO:
The COSMO method used in a MOZYME calculation has been modified to allow large systems to be calculated. The time for evaluation of solvent phase SCF is now 25% longer than that needed for a gas-phase calculation. Previously, the memory demand limited application to systems of less than 1,000 atoms, and the calculations took much longer.

Improved SCF convergence in MOZYME:
Level shifting methods have been applied to the MOZYME SCF calculation. The result of this is a more rapid and robust convergence to the SCF.

Improved evaluation of canonical molecular orbitals:
The method for evaluating eigenvectors in a MOZYME calculation has been improved to increase speed and decrease memory requirements.

Addition of new parameter sets:
Parameters are available for all non-radioactive main-group elements, Zn, Cd, and Hg for the methods MNDO, AM1, PM3, and PM5.

New method PM5:
A new parameter set, called PM5, has been added. Parameters are available for all non-radioactive main-group elements, Zn, Cd, and Hg. Except for dipole moments, the new method appears to have a higher accuracy than earlier methods.

Molecular Mechanics correction for carbon ring systems:
NDDO semiempirical methods predict some organic ring systems, such as cyclopentane, to be planar, although they are known to be puckered. To correct for this, a molecular mechanics correction can be applied.