MOMEC program

Within MM, a POS or ligand-ligand repulsion scheme removes the angle-bend term at the metal and thus reference 9q values are not required. This approach has been adopted by Hambley and Comba in their MOMEC program (17) and we have followed suit (18). 

The second solution is used in the MOMEC program and the ligand field molecular mechanics (LFMM) method as implemented in DOMMINO. In both cases, instead of using an L-M-L angle bend term, explicit ligand-ligand 1,3-nonbonded interactions are permitted which, in the spirit of VSEPR theory or points on a sphere (POS), facilitate the treatment of any coordination number. 

The repulsion increases exponentially, and it is steeper than the bond length deformation potential. The attractive force is usually modeled by a 1/r6 term, while various possibilities exist for the repulsion. The functions used in modem programs include, apart from the Morse potential (Eq. 2.13), the Lennard-Jones potential (Eq. 2.25)[401 (e.g., AMBER1411), the Buckingham potential (Eq. 2.26)[421 (e.g., MOMEC[81), or a modification thereof, the Hill potential (Eq. 2.27) (e.g., MM2, MM3[1,2,231). 

Momec[521 is a molecular mechanics program which was designed specially for coordination and inorganic compounds. It has been adapted for use with HyperChem[511. 

The tutorial has been written for the full, commercially available programs MOMEC and HyperChem but most tutorials can be completed with the MOMEClite/Hinview set of programs provided on the CD. Readers who have li-... 

MOMEC 97 [89] required Hyperchem for molecule display and building. MOMEC 3 [90] is a molecular mechanics program whidi was designed especially for coordination and inor-... 

The design of a molecule editor is a major task. To make the most of our investment, we release the full source under the GNU Public License (GP, see the Momec website for details). This means that anyone has full access to the source and can make modifications and improvements. We hope that modifications by the community together with our own continuing efforts will lead to a fast development of our program. Since the release of Momec97, the Internet has become ubiquitous. We therefore release binary versions of Momec3 as well as the source code on the Momec website. 

Much of the work invested in this third edition of our book went into writing Momec3. The tutorial of Part III has therefore been rewritten because it is based on the Momec3 program. The new version now includes its own molecular graphics and is freely available without any restrictions on its use (see www.momec.uni-hd. de). The appendices have also been updated, and regularly updated lists and comments related to the field appear on the Momec homepage. 

These issues are discussed by Comba and Hambley who also provide a detailed account of how to derive FF parameters as do Norrby and Brandt. Computer programs which have been applied to modeling various coordination compounds include versions of MM2 and MM3, SHAPES,and modified versions of MacroModel, CHARMM, AMBER,MOMEC, ... 

---