Entropic exponents of grafted lattices stars

Abstract

The surface entropic exponents of half-space lattice stars grafted at their central nodes in a hard wall are estimated numerically using the PERM algorithm. In the square half-lattice the exact values of the exponents are verified, including Barber's scaling relation and a generalisation for $2$-stars with one and two surface loops respectively. This is the relation \[ \gamma_{211}=2\,\gamma_{21}-\gamma_{20},\] where $\gamma_{21}$ and $\gamma_{211}$ are the surface entropic exponents of a grafted $2$-star with one and two surface loops respectively, and $\gamma_{20}$ is the surface entropic exponent with no surface loops. This relation is also tested in the cubic half-lattice where surface entropic exponents are estimated up to $5$-stars, including many with one or more surface loops. Barber's scaling relation and the relation \[ \gamma_{3111}=\gamma_{30}-3\,\gamma_{31}+3\,\gamma_{311} \] are also tested, where the exponents $\{\gamma_{31},\gamma_{311},\gamma_{3111}\}$ are of grafted $3$-stars with one, two or three surface loops respectively, and $\gamma_{30}$ is the surface exponent of grafted $3$-stars.