On directed Barab´asi-Albert networks with two and seven neighbours selected by each added site,the Ising model with spin S=1/2 was seen not to show a spontaneous magnetisation.Instead,the decay time for flipping...On directed Barab´asi-Albert networks with two and seven neighbours selected by each added site,the Ising model with spin S=1/2 was seen not to show a spontaneous magnetisation.Instead,the decay time for flipping of the magnetisation followed an Arrhenius law for Metropolis and Glauber algorithms,but for Wolff cluster flipping the magnetisation decayed exponentially with time.However,on these networks the Ising model spin S=1 was seen to show a spontaneous magnetisation.In this case,a first-order phase transition for values of connectivity z=2 and z=7 is well defined.On these same networks the Potts model with q=3 and 8 states is now studied through Monte Carlo simulations.We also obtained for q=3 and 8 states a first-order phase transition for values of connectivity z=2 and z=7 for the directed Barab´asi-Albert network.Theses results are different from the results obtained for the same model on two-dimensional lattices,where for q=3 the phase transition is of second order,while for q=8 the phase transition is of first-order.展开更多
On Barab´asi-Albert networks with z neighbours selected by each added site,the Ising model was seen to show a spontaneous magnetisation.This spontaneous magnetisation was found below a critical temperature which ...On Barab´asi-Albert networks with z neighbours selected by each added site,the Ising model was seen to show a spontaneous magnetisation.This spontaneous magnetisation was found below a critical temperature which increases logarithmically with system size.On these networks the majority-vote model with noise is now studied through Monte Carlo simulations.However,in this model,the order-disorder phase transition of the order parameter is well defined in this system and this was not found to increase logarithmically with system size.We calculate the value of the critical noise parameter qc for several values of connectivity z of the undirected Barab´asiAlbert network.The critical exponentesβ/ν,γ/νand 1/νwere also calculated for several values of z.展开更多
We investigate the critical properties of the Ising S=1/2 and S=1 model on(3,4,6,4)and(34,6)Archimedean lattices.The system is studied through the extensive Monte Carlo simulations.We calculate the critical temperatur...We investigate the critical properties of the Ising S=1/2 and S=1 model on(3,4,6,4)and(34,6)Archimedean lattices.The system is studied through the extensive Monte Carlo simulations.We calculate the critical temperature as well as the critical point exponentsγ/ν,β/ν,andνbasing on finite size scaling analysis.The calculated values of the critical temperature for S=1 are kBTC/J=1.590(3),and kBTC/J=2.100(4)for(3,4,6,4)and(34,6)Archimedean lattices,respectively.The critical exponentsβ/ν,γ/ν,and 1/ν,for S=1 areβ/ν=0.180(20),γ/ν=1.46(8),and 1/ν=0.83(5),for(3,4,6,4)and 0.103(8),1.44(8),and 0.94(5),for(34,6)Archimedean lattices.Obtained results differ from the Ising S=1/2 model on(3,4,6,4),(34,6)and square lattice.The evaluated effective dimensionality of the system for S=1 are Deff=1.82(4),for(3,4,6,4),and Deff=1.64(5)for(34,6).展开更多
基金the Brazilian agency FAPEPI(Teresina-Piauı-Brasil)for its financial supportalso the Fernando Whitaker for the support of the system SGI Altix 1350 the computational park CENAPAD.UNICAMP-USP,SP-BRASIL.
文摘On directed Barab´asi-Albert networks with two and seven neighbours selected by each added site,the Ising model with spin S=1/2 was seen not to show a spontaneous magnetisation.Instead,the decay time for flipping of the magnetisation followed an Arrhenius law for Metropolis and Glauber algorithms,but for Wolff cluster flipping the magnetisation decayed exponentially with time.However,on these networks the Ising model spin S=1 was seen to show a spontaneous magnetisation.In this case,a first-order phase transition for values of connectivity z=2 and z=7 is well defined.On these same networks the Potts model with q=3 and 8 states is now studied through Monte Carlo simulations.We also obtained for q=3 and 8 states a first-order phase transition for values of connectivity z=2 and z=7 for the directed Barab´asi-Albert network.Theses results are different from the results obtained for the same model on two-dimensional lattices,where for q=3 the phase transition is of second order,while for q=8 the phase transition is of first-order.
基金supported by the system SGI Altix 1350 the computational park CENAPAD.UNICAMP-USP,SP-BRAZIL.
文摘On Barab´asi-Albert networks with z neighbours selected by each added site,the Ising model was seen to show a spontaneous magnetisation.This spontaneous magnetisation was found below a critical temperature which increases logarithmically with system size.On these networks the majority-vote model with noise is now studied through Monte Carlo simulations.However,in this model,the order-disorder phase transition of the order parameter is well defined in this system and this was not found to increase logarithmically with system size.We calculate the value of the critical noise parameter qc for several values of connectivity z of the undirected Barab´asiAlbert network.The critical exponentesβ/ν,γ/νand 1/νwere also calculated for several values of z.
基金the Brazilian agency FAPEPI(Teresina,Piaui,Brazil)and the Polish Ministry of Science and Higher Education for their financial support。
文摘We investigate the critical properties of the Ising S=1/2 and S=1 model on(3,4,6,4)and(34,6)Archimedean lattices.The system is studied through the extensive Monte Carlo simulations.We calculate the critical temperature as well as the critical point exponentsγ/ν,β/ν,andνbasing on finite size scaling analysis.The calculated values of the critical temperature for S=1 are kBTC/J=1.590(3),and kBTC/J=2.100(4)for(3,4,6,4)and(34,6)Archimedean lattices,respectively.The critical exponentsβ/ν,γ/ν,and 1/ν,for S=1 areβ/ν=0.180(20),γ/ν=1.46(8),and 1/ν=0.83(5),for(3,4,6,4)and 0.103(8),1.44(8),and 0.94(5),for(34,6)Archimedean lattices.Obtained results differ from the Ising S=1/2 model on(3,4,6,4),(34,6)and square lattice.The evaluated effective dimensionality of the system for S=1 are Deff=1.82(4),for(3,4,6,4),and Deff=1.64(5)for(34,6).
