The zwitterion isomer of orthosilicic acid and its role in neutral pH dimerization from density functional theory.

28 July 2021, Version 2
This content is a preprint and has not undergone peer review at the time of posting.


Using density functional theory, the plausible existence of the zwitterion isomer of orthosilicic acid is proposed to account for some of the properties of silica in water. Explicit hydration and explicit addition of salt are used in modeling the zwitterion and the dimerization reaction. Paths between orthosilicic acid, the zwitterion and the autoionization products are presented. The pK for the formation of the aqueous zwitterion species is calculated to be 7.78 in dilute silica solutions and the activation energy for the dimerization reaction ranges from 59.8 kJ/mol to 70.7 kJ/mol depending on salt concentration.


orthosilicic acid
disilicic acid
density functional theory
ab initio
explicit hydration
activation energy

Supplementary materials

Research Data
Configurations of molecules used in this study. Also, excerpts from Gaussian frequency calculations for these configurations.


Comments are not moderated before they are posted, but they can be removed by the site moderators if they are found to be in contravention of our Commenting Policy [opens in a new tab] - please read this policy before you post. Comments should be used for scholarly discussion of the content in question. You can find more information about how to use the commenting feature here [opens in a new tab] .
This site is protected by reCAPTCHA and the Google Privacy Policy [opens in a new tab] and Terms of Service [opens in a new tab] apply.