  This paper contributes new insights into discretizing Coulomb collisions in
kinetic plasma models. Building on the previous works [Carrillo et al. J. Comp.
Phys. X 7:100066 (2020), Hirvijoki and Burby Phys. Plasmas 27(8):082307
(2020)], I propose deterministic discrete-time energy- and
positivity-preserving, entropy-dissipating marker-particle schemes for the
standard Landau collision operator and the electrostatic gyrokinetic Landau
operator. In case of the standard Landau operator, the scheme preserves also
the discrete-time kinetic momentum. The improvements, the extensions of the
structure-preserving discretizations in [Carrillo et al. J. Comp. Phys. X
7:100066 (2020), Hirvijoki and Burby Phys. Plasmas 27(8):082307 (2020)] to
discrete time, are made possible by exploiting the underlying metriplectic
structure of the collision operators involved and the so-called
discrete-gradient integrators.
