Structure and dynamics of a driven polymer on a smooth cylindrical surface are studied by Brownian dynamics simulations. The effect of driven force on the polymer adsorption behavior and the...

The structures and energies of the B and Ga incorporated -alumina surface as well as the adsorption of water are investigated using dispersion corrected density functional theory. The results show that the substitution of surface Al atom by B atom is not so favored as Ga atom. The substitution reaction prefers to occur at the tricoordinated A(4) sites. However, the substitution reaction becomes less thermodynamically favored when more Al atoms are substituted by B and Ga atoms on the surface. Moreover, the substitution of bulk Al atoms is not so favored as the Al atoms by B and Ga on the surface. The -alumina surface is found to have stronger adsorption ability for water than the B and Ga incorporated surface. The total adsorption energy increases as water coverage increases, while the stepwise adsorption energy decreases. The studies show the coverage of water at 7.5 H 2 O/nm 2 (five H 2 O molecules per unit cell) can fully cover the active sites and the further water molecule could only be physically adsorbed on the surface.

Inspired by the eccentricity design of self-driven disks, we propose a computational model to study the remarkable behavior of this kind of active matter via Langevin dynamics simulations. We pay attention to the effect of rotational friction coefficient and rotational noise on the phase behavior. A homogeneous system without rotational noise exhibits a sharp discontinuous transition of orientational order from an isotropic to a polar state with the increase of rotational friction coefficient. When there is rotational noise, the transition becomes continuous. The formation of polar state originates from the effective alignment effect due to the mutual coupling of the positional and orientational degrees of freedom of each disk. The rotational noise could weaken the alignment effect and cause the large spatial density inhomogeneity, while the translational noise homogenizes the system. Our model makes further conceptual progress on how the microscopic interaction among self-driven agents yields effective alignment.