[gmx-users] Enthalpy of vaporization

Eric Jakobsson jake at ncsa.uiuc.edu
Mon Jan 5 22:26:02 CET 2004

A possibly useful reference for vdw parameters for unit carbon atoms in 
hydrocarbons is:

Chiu, S. W., Clark, M. M., Jakobsson, E., Subramaniam, S., and H. L. Scott. 
1999b. Optimizations of hydrocarbon chain interaction parameters: 
Application to the simulation of fluid phase lipid bilayers.  J. Phys. 
Chem.  B 103:6323-6327

The main point is that in order to get the parameters right, you need to 
simulate the density at constant pressure for plymers with the same 
building blocks, but different numbers of them.  In that case at least, the 
same parameters that worked for the density also made the heat of 
vaporization about right.


At 07:20 PM 1/5/2004 +0100, you wrote:
>On Mon, 5 Jan 2004, Pedro Alexandre Lapido Loureiro wrote:
> >Hi!
> >
> >I am doing a parametrization of small alkane with halogen atoms.
> >When the density is good, the DHvap is not (6 kcal/mol - experimental 
> and 11
> >kcal/mol - my simulation) and vice versa.
> >For the calculation, I am using: DHvap = RT - Einter(liquid state).
> >To what extent should I expect to reproduce the experimental DHvap value?
>Better than 6, within 2 kJ/mole, but not for all possible halogenated
>compounds. Can you be more specific? Is this within the OPLS (all-atom)
>force field?
>Gromacs does have specific options for parameterizing.
> >Regards,
> >
> >Pedro.
> >--
> >Pedro Alexandre Lapido Loureiro
> >Laboratório de Física Biológica
> >Instituto de Biofísica
> >Brasil
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Eric Jakobsson, Ph.D.
Professor, Department of Molecular and Integrative Physiology, and of 
Senior Research Scientist, National Center for Supercomputing Applications
Professor, Beckman Institute for Advanced Science and Technology
4021 Beckman Institute, mc251
University of Illinois, Urbana, IL 61801
ph. 217-244-2896       fax 217-244-2909
(Currently on leave to the National Institutes of Health in Bethesda, 
Maryland, to be Director of the NIGMS Center for Bioinformatics and 
Computational Biology and Chair of the NIH Biomedical Information Science 
and Technology Initiative Consortium, but maintaining my research lab at 
Illinois by periodic commuting.  My usual schedule is four days a week at 
NIH and three days a week at Illinois.)

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