Friction, mobility, and thermophoresis of carbon nanoparticles on a graphene sheet

It is shown using the method of molecular dynamics that motion carbon nanoparticles (rectangular graphene flakes, spherical fullerenes size $L<10$ nm) on surface a thermalized sheet lying flat substrate can be described as particles in viscous medium with constant coefficient friction, value which depends temperature and particle size. has been there are two types effective friction: diffusion ballistic. In ballistic regime (at velocities $v>200$ m/s), deceleration occurs due to interaction moving thermal out-of-plane bending vibrations sheet. Because this, increasing temperature, friction monotonically increases. $v<20$ arises need for overcome local energy barriers, therefore it decreases temperature. The difference between most pronounced at low temperatures, since mobility while monotonously Thermophoresis modeling shows large values gradient along substrate, mode realized. this mode, does not depend their shape size, but determined only by gradient. presence normal force pressing nanoparticle leads an increase its substrate.