[gmx-users] Re: Heat of Vaporization

[Dr. Vitaly V. Chaban]

>
> 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.
>

What is your system?


(1a) is what everyone does.

-- 
Dr. Vitaly V. Chaban, 430 Hutchison Hall, Chem. Dept.
Univ. Rochester, Rochester, New York 14627-0216
THE UNITED STATES OF AMERICA