The influence of nonequilibrium initial values of the order parameter on its evolution at a critical point is described using a renormalization group approach of the field theory. The dynamic critical exponent θ ′ of the short time evolution of a system with an n-component order parameter is calculated within a dynamical dissipative model using the method of ε-expansion in a threeloop approximation. Numerical values of θ ′ for three-dimensional systems are determined using the Padé-Borel method for the summation of asymptotic series.

No abstract

No abstract

No abstract

Renormalization-group approach is applied to investigate the short-time nonequilibriumcritical behavior of pure and diluted spin systems with nonmagnetic point-like impurities.The dissipative relaxation dynamics with non-conserved order parameter is considered. For thefirst time the description of the order parameter growth induced by the initial nonequilibriumstate of system is carried out at fixed dimension d = 3 without use of ε-expansion.