QuacPac 1.3

QUACPAC offers everything necessary to do charges well. As the chemistry of molecular interactions is a matter of shape and electrostatics, accurate or at least consistent charge representation is critical in drug design. However even the best charge models are of limited value if protonation states are wrong.
QUACPAC provides pKa and tautomer enumeration in order to get correct protonation states. It also offers multiple partial charge models (including MMFF94 [1] and AM1-BCC [2]) that cover a range of speed and quality in order to allow appropriate charging for every end use.
QUACPAC's approach to tautomeric enumeration is to provide multiple tautomeric states rather than one "correct" tautomer. Subsequent downstream processes are then used to identify the appropriate tautomeric form.