Extension of the PDDG/PM3 Semiempirical Molecular Orbital Method to Sulfur, Silicon, and Phosphorus.

ABSTRACT: The PDDG/PM3 semiempirical molecular orbital method has been parameterized for molecules, ions, and complexes containing sulfur; the mean absolute error (MAE) for heats of formation, DeltaH(f), of 6.4 kcal/mol is 35 - 40 % smaller than for PM3, AM1, and MNDO/d. For completeness, parameterization was also carried out for silicon and phosphorous. For 144 silicon-containing molecules, the DeltaH(f) MAE for PDDG/PM3, PM3, and AM1 is 11 - 12 kcal/mol, while MNDO/d yields 9.4 kcal/mol. For the limited set of 43 phosphorus-containing molecules, MNDO/d also yields the best results followed by PDDG/PM3, AM1, and PM3. The benefits of the d-orbitals in MNDO/d for hypervalent compounds are apparent for silicon and phosphorous, while they are masked in the larger dataset for sulfur by large errors for

SUBMITTER: Tubert-Brohman I 

PROVIDER: S-EPMC2582878 | biostudies-literature | 2005

REPOSITORIES: biostudies-literature