A comparison of conformational energies calculated by molecular mechanics (MM2(85), Sybyl 5.1, Sybyl 5.21, and ChemX) and semiempirical (AM1 and PM3) methods

✍ Scribed by Klaus Gundertofte; Jonas Palm; Ingrid Pettersson; Anders Stamvik

• Publisher: John Wiley and Sons
• Year: 1991
• Tongue: English
• Weight: 778 KB
• Volume: 12
• Category: Article
• ISSN: 0192-8651
• DOI: 10.1002/jcc.540120209

✦ Synopsis

Conformational energies of different conformers have been calculated for a series of molecules using various molecular mechanics and semiempirical methods. The quality of the force fields has also been tested by calculating barriers to rotation about carbon-carbon bonds. The molecular mechanics force fields used are MM2(85), Syby15.1, Sybyl5.21, and ChemX, ver. Jan 89. The semiempirical methods used are AM1 and PM3. Molecules with different functional groups, for which good experimental data exist, have been selected. The semiempirical methods generally calculate barriers to rotation which are lower than the experimentally determined. The conformational energies for hydrocarbons are reasonably well reproduced by all tested methods although MMZ(85) gives the quantitatively best agreement with experiments. For compounds containing oxygen, nitrogen and halogens MMZ(85) gives results which are in best agreement with the experimentally determined values.