J. Phys. II France
Volume 1, Numéro 2, February 1991
Page(s) 135 - 147
DOI: 10.1051/jp2:1991152
J. Phys. II France 1 (1991) 135-147

Weak crystallisation theory of the ${\rm A}_{1}$- $\tilde{\rm A}$ and ${\rm A}_{1}$- $
\tilde{\rm C}$ phase transitions

V. V. Lebedev1 and A. R. Muratov2

1  USSR academy of sciences, L.D. Landau Institute for theoretical physics, 117940, GSP-1, Moscow, V-334, Kosygina, 2
2  USSR academy of sciences, Institute of oil and gas research, 117917, Moscow, V-296, Leninsky prospect, 65

(Received 25 June 1990, revised 12 November 1990, accepted 16 November 1990)

Peculiarities of A 1- $\tilde{\rm A}$, A 1- $
\tilde{\rm C}$ phase transitions are considered in the framework of weak crystallization theory. Fluctuation effects are taken into account. The topology of the phase diagram including the A 1, $\tilde{\rm A}$, $
\tilde{\rm C}$ phases is found. The singularities of different physical quantities near the phase transitions are investigated. The form of the pair correlation function is computed. The results may be compared with the data obtained in heat capacity and X-ray experiments.

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