Quacpac TK 1.6.0

New features

• The default AM1BCC charge model OECharges_AM1BCC now lightly restrains the AM1 geometry optimization to the starting coordinates. This allows the important relaxation of bond and angle degrees of freedom while greatly reducing the potential to alter the molecule’s conformation away from its starting coordinates. AM1 geometry optimization can be suppressed with OECharges_AM1BCCSPt or OECharges_AM1BCCNoSymSPt.

Bug fixes

• The AM1BCC charge models OECharges_AM1BCCSym and OECharges_AM1BCCSPt now symmetrize the partial charges over bond-topologically equivalent atoms, e.g. methyl hydrogens, in keeping with the original model. This is especially important with conformationally flexible molecules. This behavior can be suppressed by using the default OECharges_AM1BCC or the non-default models OECharges_AM1BCCNoSym or OECharges_AM1BCCNoSymSPt.