Re: [AMBER] About amber parameters for free dioxygen in water solution

From: Jason Swails <>
Date: Sat, 3 Jan 2015 07:51:06 -0500

> On Jan 3, 2015, at 4:27 AM, Francesco Pietra <> wrote:
> Hi:
> The last mention in this forum about (unavailable) amber parameters for
> free dioxygen in solution dates to 2009. Has anyone knowledge of recently
> validating such (non-polarizable) parameters? Perhaps from experimental
> data, as quantum calculations with triplet O2 remain problematic.

This isn’t actually quite as hard to do with classical force fields as it is with QM. Unlike QM, the fact that O2 is a ground state triplet doesn’t actually affect fixed-charge force field parameters... we do not formally acknowledge the existence of these so-called “electrons” or “wave functions”.

The charge for O2 is easy -- 0. The van der Waals parameters are potentially more difficult, but I would derive those by reproducing experimental bulk properties rather than anything based on QM calculations in this particular case.


> thanks
> francesco pietra
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Jason M. Swails
Rutgers University
Postdoctoral Researcher
AMBER mailing list
Received on Sat Jan 03 2015 - 05:00:02 PST
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