  The different variants of two-stage random sequential adsorption (RSA) models
for packing of disks and discorectangles on a two-dimensional (2D) surface were
investigated. In the SD model, the discorectangles were first deposited and
then the disks were added. In the DS model, the disks were first deposited and
then discorectangles were added. At the first stage the particles were
deposited up to the selected concentration and at the final (second) stage the
particles were deposited up to the saturated (jamming) state. The main
parameters of the models were the concentration of particles deposited at the
first stage, aspect ratio of the discorectangles $\varepsilon$ (length to
diameter of ratio $\varepsilon=l/d$) and disk diameter $D$. All distances were
measured using the value of $d$ as a unit of measurement of linear dimensions,
the disk diameter was varied in the interval $D \in [1-10]$, and the aspect
ratio value was varied in the interval $\varepsilon\in [1-50]$. The
dependencies of the jamming coverage of particles deposited at the second stage
versus the parameters of the models were analyzed. The presence of first
deposited particles for both models regulated the maximum possible disk
diameter, $D_{max}$ (SD model) or the maximum aspect ratio, $\varepsilon_{max}$
(DS model). This behavior was explained by the deposition of particles in the
second stage into triangular (SD model) or elongated (DS model) pores formed by
particles deposited at the first stage. The percolation connectivity of disks
(SD model) and discorectangles (DS model) for the particles with a hard core
and a soft shell structure was analyzed. The disconnectedness was ensured by
overlapping of soft shells. The dependencies of connectivity versus the
parameters of SD and DS models were also analyzed.
