Effective pressure due to surface tension
Posted: Tue May 31, 2011 1:04 pm
I interested in calculating an 'effective pressure' on a nanoparticle created by surface tension.
My starting point is the Young-Laplace equation for the effective pressure on a droplet/meniscus which states
Peff=2*(sigma)/<R>
where sigma is the surface tension and <R> is the radius of the droplet/meniscus (in the case of a nanoparticle the average radius).
Therefore I am interested in finding out the surface stress set up in a relaxed surface. However this needs to be a scalar quantity for the purpose of applying the Y-LP eq.
I am under instruction to take the VASP calculation of external pressure, which contains in-plane and off-diagonal terms due to the relaxation of the surface atoms, and in order to account for the redundant direction (normal to the surface, where there no stress exists) multiply this by the slab thickness to gain an effective, isotropic surface stress.
Can anyone comment on the nature of this approach?
My starting point is the Young-Laplace equation for the effective pressure on a droplet/meniscus which states
Peff=2*(sigma)/<R>
where sigma is the surface tension and <R> is the radius of the droplet/meniscus (in the case of a nanoparticle the average radius).
Therefore I am interested in finding out the surface stress set up in a relaxed surface. However this needs to be a scalar quantity for the purpose of applying the Y-LP eq.
I am under instruction to take the VASP calculation of external pressure, which contains in-plane and off-diagonal terms due to the relaxation of the surface atoms, and in order to account for the redundant direction (normal to the surface, where there no stress exists) multiply this by the slab thickness to gain an effective, isotropic surface stress.
Can anyone comment on the nature of this approach?