Re: AMBER: Heat of Vaporization

From: David A. Case <>
Date: Tue, 15 May 2007 09:51:36 -0700

On Tue, May 15, 2007, David A. Case wrote:

> On Tue, May 15, 2007, Rita Cassia wrote:
> >
> > I would like to know how to do a md simulation with cutoff set to 0.
> What happens if you just try it? Comment out the section in mdread.f
> that stops because this is "unreasonably small".

I just noticed that your subject said "Heat of vaporization". Setting the
cutoff of zero would *not* be the way to compute a heat of vaporization.
You need to to a separate simulation with a single gas-phase molecule to get
the "gas" side of the equation.

Here's a paper with a very nice discussion on how to compute heats of
vaporization (it's harder than most people think!):

%A H.W. Horn
%A W.C. Swope
%A J.W. Pitera
%A J.D. Madura
%A T.J. Dick
%A G.L. Hura
%A T. Head-Gordon
%T Development of an improved four-site water model for biomolecular
%simulations: TIP4P-Ew
%J J. Chem. Phys.
%V 120
%P 9665-9678
%D 2004

If you want to go further, to get the vapor pressure and so on:

%A H.W. Horn
%A W.C. Swope
%A J.W. Pitera
%T Characterization of the TIP4P-Ew water model: Vapor pressure and boiling
%J J. Chem. Phys.
%V 123
%P 194504
%D 2005

...hope this helps...dac

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Received on Wed May 16 2007 - 06:07:33 PDT
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