ELFT HÍRADÓ

[Szeminárium koordinátor <sem-admin AT szfki.hu>]

SZFI SeminarShengfeng DengCentre for Energy ResearchCoupled two-species model 
for the pair contact process with diffusionTuesday, 14 September 2021, 10:00, 
Teams, 
https://teams.microsoft.com/l/meetup-join/19%3ace423c05cd1543ab9f9905886590ad69%40thread.tacv2/1630940331924?context=%7b%22Tid%22%3a%224d7ddeef-14ff-4911-8c11-401c69384d77%22%2c%22Oid%22%3a%22969d2d4a-5ba8-43f1-bd69-93f0998b025f%22%7dThe
 pair contact process with diffusion (PCPD) defined by the binary reactions B 
+ B → B + B + B, B + B → ∅ and diffusive particle spreading exhibits an 
unusual active to absorbing phase transition whose universality class has 
long been disputed. Such reactions may also be related to certain catalytic 
reactions. Multiple studies have indicated that an explicit account of 
particle pair degrees of freedom may be required to properly capture this 
system’s effective long-time, large-scale behavior. We introduce a 
two-species representation for the PCPD in which single particles B and 
particle pairs A are dynamically coupled according to the stochastic reaction 
processes B + B → A, A → A + B, A → ∅, and A → B + B, with each particle type 
diffusing independently. Mean-field analysis reveals that the phase 
transition of this model is driven by competition and balance between the two 
species. We employ Monte Carlo simulations in one, two, and three dimensions 
to demonstrate that this model consistently captures the pertinent features 
of the PCPD. In the inactive phase, A particles rapidly go extinct, 
effectively leaving the B species to undergo pure diffusion-limited pair 
annihilation kinetics B + B → ∅. At criticality, both A and B densities decay 
with the same exponents as the corresponding order parameters of the original 
PCPD, and display mean-field scaling above the upper critical dimension dc = 
2. In one dimension, the critical exponents for the B species obtained from 
seed simulations also agree well with previously reported exponent value 
ranges. We demonstrate that the scaling properties of consecutive particle 
pairs in the PCPD are identical with that of the A species in the coupled 
model. This two-species picture resolves the conceptual difficulty for seed 
simulations in the original PCPD and naturally introduces multiple length 
scales and time scales to the system, which are also the origin of strong 
corrections to scaling. The extracted moment ratios from our simulations 
indicate that our model displays the same temporal crossover behavior as the 
PCPD, which further corroborates its full dynamical equivalence with our 
coupled model. Minden érdeklődőt szívesen látunk! - Everyone is welcome 
to attend.Róbert Juhászsem-admin AT szfki.hu