G09 uses a new algorithm to make the overlaps generate a smoother surface. These ‘magic numbers’ (I hate the term) were used to modify the way by which the overlapping spheres were treated in order to create the surface which in turn defined the cavity. My previous post on PCM mentioned the usage of the options OFac=0.8 & RMin=0.5 as part of the additional input. In order to include these terms during the SCF procedure, and to have them reported separately, the SCRF=SMD option should be used. These non-electrosatic interactions are no longer calculated in the default. Gaussian 03 used to calculate and report non-electrostatic contributions to the solvation energy, however they were not included in the total energy nor during optimization procedures.
However, the absolute solvation energy now requires a gas-phase optimization along with a frequency calculation followed by the same calculations with the SCRF=SMD option in the desired solvent and with the appropriate variables. It is now replaced by DoVacuum which should be included in the SCRF options as SCRF=(DoVacuum,etc.). The SCFVAC keyword used to calculate the Gibbs Solvation Energy change is no longer available. However there are some differences in the SCRF modules between G09 and G03 and I here present some of them as well as some tips to work with the new version. The FINAL SINGLE POINT ENERGY now already includes all computed solvation terms. The Charge-correction term is not included in the SCF energy, and is just printed for information purposes.
GAUSSIAN SOLVENT FREE
Components : Nuclear Repulsion : 765.01084602 Eh 20817.00344 eV Electronic Energy : - 1413.26452682 Eh - 38456.88288 eV One Electron Energy : - 2400.58284083 Eh - 65323.18007 eV Two Electron Energy : 987.31831400 Eh 26866.29718 eV CPCM Dielectric : - 0.01874113 Eh - 0.50997 eV CPCM Solvation Model Properties : Surface - charge : - 0.01502552 Charge - correction : - 0.00002872 Eh - 0.00078 eV Free - energy ( cav + disp ) : This term is not implemented in the current solvation schemeĪs one can see, dielectric contribution to the energy, the solute net charge, the charge and cavity corrections are printed separately (the latter in this case is not calculated).
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