Critical properties of the reaction - diffusion model 2A -> 3A, 2A ->0

Abstract

The steady-state phase diagram of the one-dimensional reaction-diffusion model 2A -> 3A, 2A -> 0 is studied through the non-hermitian density matrix renormalization group. In the absence of single-particle diffusion the model reduces to the pair-contact process, which has a phase transition in the universality class of Directed Percolation (DP) and an infinite number of absorbing steady states. When single-particle diffusion is added, the number of absorbing steady states is reduced to two and the model does not show DP critical behaviour anymore. The exponents $θ=ν_{\|}/ν_{\perp}$ and $β/ν_{\perp}$ are calculated numerically. The value of $β/ν_{\perp}$ is close to the value of the Parity Conserving universality class, in spite of the absence of local conservation laws.

Substantially revised version, RevTeX, 10 Pages and 5 PostScript figures included