TABLE II.
Errors in structural properties of different parameterizations of the SCC-DFTB approach or common phosphate compoundsa
Geometrical Parameterb | Second-order | SCC-DFTBPAc | SCC-DFTBPR |
---|---|---|---|
P-O (Å) | 0.03 | 0.04 | 0.03 |
O-P-O (°) | 1.8 | 1.9 | 1.7 |
The root-mean-square (RMS) errors are calculated relative to those from B3LYP/6-31+G(d,p) alculations.
In total, 10 common phosphate compounds are included in the analysis (including MMP/DMP-water complexes, pentavalent intermediate structures for the hydrolysis of MMP/DMP, different protonation states for phosphoric acid, models for ADP and ATP). For selected structures, see Fig. 1.
With SCC-DFTBPA, the pentavalent intermediate for MMP hydrolysis is not stable as an intermediate, and geometry optimization leads to the reactant state.