Dear CCLers,

Jan Labanowski has kindly posted on the Computational Chemistry List
archives a force-field evaluation suite that is geared to assessing performance 
for reproducing conformational energies and for producing reasonable values and 
trends for intermolecular-interaction energies and geometries.  This evaluation 
suite provides the input data and a summary of principal results for the 
following manuscript:

T. A. Halgren, "MMFF VII. Characterization of MMFF94, MMFF94s, and Other
Widely Available Force Fields for Conformational Energies and for
Intermolecular-Interaction Energies and Geometries," J. Comput. Chem., 
in press (expected out in April 1999).

As most of the reference ab initio structures are MP2(FULL)/6-31G*-optimized 
structures, the suite can also be used for testing or parameterizing force-field
geometries.  

Input data are provided for three sets of conformational energy comparisons. 
The first uses the 37 comparisons to experiment employed in the original MMFF94 
paper on this subject (T. A. Halgren and R. B. Nachbar, J. Comput. Chem., 17, 
587-615 (1996)); reference "MP4SDQ/TZP" and GVB-LMP2/cc-pVTZ(-f) energies 
are also provided.  The second set consists of 19 comparisons to experiment 
taken from K. Gundertofte, T. Liljefors, P.-O. Norrby, and I. Petterssen, J. 
Comput. Chem., 17, 429-449 (1996) for which neither ab initio nor experimental 
data were used in the development of MMFF94.  The third set consists of 147 
comparisons to ab initio values obtained at the composite "MP4SDQ/TZP" level.
For Sets 1 and 3, the input structures are MP2(FULL)/6-31G*-optimized
structures; for Set 2, MMFF94-optimized structures that can serve as a useful
starting place for optimizations using other methods are provided.

Input data are also provided for comparisons of intermolecular-interaction 
energies and geometries to scaled HF/6-31G* results for the 66 small-molecule 
dimers used in the nonbonded parameterization of MMFF94 (T. A. Halgren, J. 
Comput. Chem., 17, 520-552 (1996)). 

Two postscript files provide tables that summarize the overall success of the 
fits to experimental or ab initio data for the various theoretical methods.  

In all, the evaluation suite contains 25 files. A README file (or, for Web 
browsers, its html equivalent) explains the role of each.

Please note also that a revised and updated MMFF94 validation suite has been 
posted elsewhere on the CCL archives.  

The force-field evaluation suite can be accessed at:

ftp://www.ccl.net/pub/chemistry/data/ff_evaluation_suite

or at:

http://www.ccl.net/cca/data/ff_evaluation_suite

I would be pleased to hear of any uses made of this data.

                                                        Best regards,


                                                        Tom Halgren

                                                        voice: 732-594-7735
                                                        fax: 732-594-4224
                                                        halgren@merck.com