Validation suite for MMFF94s (see J. Comp. Chem., May 1999 issue)

Dear CCLers,
 Jan Labanowski has kindly posted on the Computational Chemistry List
 archives a validation suite for MMFF94s.  As described in a paper just out
 (T. A. Halgren, J. Comput. Chem., 20, 720-729 (1999)), MMFF94s differs from
 MMFF94 in that it employs modified parameters that serve to make trigonal
 delocalized nitrogens in structures such as amides, enamines, anilines, and
 nucleotide bases planar or nearly so.  As a result, energy-optimized MMFF94s
 structures resemble common experimentally determined structures, such as
 X-ray
 structures, much more closely than do optimized MMFF94 structures; such
 experimental structures reflect time-averaged atomic coordinates in addition
 to the effects of condensed-phase interactions that theoretical calculations
 show also promote planarity at nitrogen.
 The suite contains a README file (or, for Web browsers, its html equivalent)
 that defines the files in the validation suite.  The most important are:
 MMFF94s_dative.mol2                 mol2-format input, using dative bonds
 for
                                                          certain sulfur and
 phosphorous compounds
 MMFF94s_hypervalent.mol2      SYBYL mol2 input, using "hypervalent"
                                                          representations
 MMFF94s.mmd                             BatchMin/MacroModel dat-format input
 MMFF94s.energies                      list of BatchMin and Merck-OPTIMOL
 total
                                                          energies
 MMFF94s_bmin.log                     BatchMin output log file
 MMFF94s_opti.log                       OPTIMOL output file with detailed
                                                         interaction analyses
 These input and output files provide data for the validation suite, which
 consists of the 235 molecules in the 761-membered MMFF94 validation suite
 for which MMFF94 and MMFF94s give different results.
 Most of the input data is derived from CSD structures.  I wish to thank
 Steve Salisbury and the Cambridge Crystallographic Data Center for
 graciously consenting to the use of this data.  I also wish to thank Jan
 Labanowski for his encouragement in the posting of this validation suite and
 for his role in providing CCL and its archives to the community.
 My hope is that this data will assist members of the community who wish to
 implement MMFF94s to validate their efforts.
 This validation suite is also intended allow individuals who use an
 independently developed commercial implementation of MMFF94s to carry out
 their
 own validation and to satisfy themselves as to its authenticity.
 The MMFF94s validation suite can be accessed at:
       http://www.ccl.net/cca/data/MMFF94s
       http://server.ccl.net/cca/data/MMFF94s
       ftp://ftp.ccl.net/pub/chemistry/data/MMFF94s
 or via anonymnous ftp at:
       ftp.ccl.net; cd to pub/chemistry/data/MMFF94s.
 The corresponding MMFF94 validation has the same address but without the
 final "s".
 I would be pleased to hear of any use made of this data.
                                                         Best regards,
                                                         Tom Halgren
                                                         voice: 732-594-7735
                                                         fax: 732-594-4224
                                                         halgren' at \`merck.com