Van der Waal's approach in the theory of phase transitions in complex plasmas

Van der Waal's approach is used to describe the equation of state of complex plasmas with dust-dust interactions including: the screened Coulomb interaction, long range non-collective repulsion, shadow non-collective attraction and collective interactions. For both cases, where either the collective or non-collective dust-dust attraction is present, the critical values of the coupling parameter Gamma(d,cr) are found (Gamma(d) = Q(2)n(d)(1/3)/T-d, Q is the dust charge, n(d) is the dust density and T-d is the dust temperature). The critical values of Gamma depend on effectiveness of the attraction and for non-collective attraction depend also on the size of the system. In substantially large complex plasma systems where the transitions to the crystal and liquid states were observed the collective attraction is operating and for small sizes systems corresponding to the complex plasma clusters the non-collective attraction is operating. The theoretical results obtained from Van der Waal's approach are compared with observations. It is shown that the phase transitions are not possible for a pure screened Coulomb (Yukawa) interactions. (C) 2003 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.