[gmx-users] droplet

[Christian Blau]

Hi Alex,


I'm not sure this is really something for the GROMACS mailing list and I'm guessing the question you were asking - What 
is the expected behaviour of the solvent accessible surface area of a droplet with temperature?

Here is a "back-of-the envelope" estimate: The easiest model of a droplet is an effective harmonic potential that keeps 
together a bunch of molecules at the center of the coordinate system. A molecule at x has then the effective potential 
energy (chemical potential) E(x) = k * x^2, yielding a Boltzmann distribution of particle positions at a given 
temperature proportional to exp(-(kx^2)/(k_b T)). The droplet boundary is an iso-contour of this distribution - 
proportional to 1/T - the surface area is thus proportional to (1/T)^2. In an equilibrium situation you would expect 
your droplet SASA to go with T^(-2). Because quenching includes non-equilibrium effects, you might observe an exponent > -2.


Best,

Christian

On 11/18/19 10:28 PM, Alex wrote:
> Dear all,
> The surface area (calculated by gmx sasa) of a droplet of a molecule,
> reduces during temperature quenching, I wonder if anybody has an idea to
> explain that by calculation a meaningful quantity of the droplet?
>
> Thank you
> Alex