Random Sequential Adsorption Approach

An adsorbing (virtual) particle is created whose position and orientation is selected at random within prescribed limits defining the simulation domain. 

If the virtual particle fulfils prescribed criteria, it is adsorbed with unit probability and its position remains unchanged during the entire simulation process (localized and irreversible deposition postulate). 

If the criteria are violated, for example, if the particles overlap, a new deposition attempt is made that is fully uncorrelated with previous attempts. 

For spherical particles one can define Sg unequivocally as jta so 0p = na Nf/AS. For non-spherical (anisotropic) particles the choice of the characteristic cross-section is not unique, however. 

The basic RSA simulation scheme is applicable not only for the quasi-continuous deposition regime but also for deposition at surface features of various shapes and dimensions. 

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A simple analytical expression is proposed for the area available to a disk on a surface for a Random Sequential Adsorption (RSA) of binary mixtures of disks. The expression was obtained by combining the low-order terms of the density expansion of the available area with the asymptotic behaviour of the surface coverage near the jamming point. Comparison with Monte Carlo simulations shows that this approach provides a fair estimation of the jamming coverage for both kinds of disks. 

The theoretical approaches aimed at a description of nonlinear adsorption regimes are discussed next—in particular the elassieal, random sequential adsorption (RSA) model. The role of polydispersity, particle shape, orientation, and electrostatic interactions is elucidated. Then, the generalized RSA model is presented, which reflects the coupling of the surface transport with the bulk transfer step governed by external force or diffusion. 

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