Chemistry

   

Accuracy of Computational Solvation Free Energies for Neutral and Ionic Compounds: Dependence on Level of Theory and Solvent Model

Authors: Sierra Rayne, Kaya Forest

Gas to aqueous phase standard state (1 atm to 1 mol/L; 298.15 K) free energies of solvation (ΔGosolv) were calculated for a range of neutral and ionic inorganic and organic compounds using various levels and combinations of Hartree-Fock and density functional theory (DFT) and composite methods (CBS-Q//B3, G4MP2, and G4) with the IEFPCM-UFF, CPCM, and SMD solvation models in Gaussian 09 (G09). For a subset of highly polar and generally polyfunctional neutral organic compounds previously identified as problematic for prior solvation models, we find significantly reduced ΔGosolv errors using the revised solvent models in G09. The use of composite methods for these compounds also substantially reduces their apparent ΔGosolv errors. In contrast, no general level of theory effects between the B3LYP/6-31+G** and G4 methods were observed on a suite of simpler neutral, anionic, and cationic molecules commonly used to benchmark solvation models. Further investigations on mono- and polyhalogenated short chain alkanes and alkenes and other possibly difficult functional groups also revealed significant ΔGosolv error reductions by increasing the level of theory from DFT to G4. Future solvent model benchmarking efforts should include high level composite method calculations to allow better discrimination of potential error sources between the levels of theory and the solvation models.

Comments: 22 Pages.

Download: PDF

Submission history

[v1] 2013-01-28 14:28:07

Unique-IP document downloads: 3148 times

Vixra.org is a pre-print repository rather than a journal. Articles hosted may not yet have been verified by peer-review and should be treated as preliminary. In particular, anything that appears to include financial or legal advice or proposed medical treatments should be treated with due caution. Vixra.org will not be responsible for any consequences of actions that result from any form of use of any documents on this website.

Add your own feedback and questions here:
You are equally welcome to be positive or negative about any paper but please be polite. If you are being critical you must mention at least one specific error, otherwise your comment will be deleted as unhelpful.

comments powered by Disqus