[gmx-users] Heat of Vaporization

[Elisabeth]

Hello,

I wanted to know your ideas on calculation of heat of vaporization using a
single phase run rather than running two separate simulations for liquid and
gas!

1- Two separate simulations for liquid and gas

DHvap = <Ugas> - <Uliq> + RT

1a: <total liquid potential> - <*total* potential of a single chain in vacu
> ( bond+angle+torsion + nonbonded interaction of chain with itself)

or

 1b: *<total liquid potential> - < intra potential of a single chain in vacu
> ( bond+angle+torsion) *

2- Single liquid phase run: (non need to run in vacu)

2a : DHvap = <total liquid potential> - < intra molecular potential terms in
liquid phase> (same liquid phase simulation by adding up bond+angle+torsion
terms)

2a: In other worlds *DHvap= <Uliq-nonbonded (vdw+electrostatics)> *

In my case the latter definition is giving much more accurate results than
1a.

I would like to know your idea and comments on methods 1b and 2a.

Appreciate your comments.

Best,
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