This is Schroedinger, Inc's 2D coordinate generation.  It was formerly
proprietary code, but is now released under the BSD license.

The emphasis of these algorithms are on quality of 2D coordinates rather than
speed of generation.  The algorithm distinguishes itself from many others by
doing well with both macrocycles and metal complexes.  It also does extremely
well on typical drug-like small molecules, and has been validated on millions
of compounds.