Martynov and Sarkisov proposed an expansion of the bridge function in terms of basis functions:
where is the chosen basis function and are the coefficients determined from thermodynamic consistency conditions. The Martynov-Sarkisov closure is based on the expansion of the bridge function in powers of the thermal potential.
where is the thermal potential and . (This closure formed the basis for the Ballone-Pastore-Galli-Gazzillo closure for hard sphere mixtures). Charpentier and Jaske  have observed that the value of differs drastically from 0.5 for temperatures greater than , thus the Martynov-Sarkisov closure is deficient in the supercritical domain.
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- I. Charpentier and N. Jakse "Exact numerical derivatives of the pair-correlation function of simple liquids using the tangent linear method", Journal of Chemical Physics 114 pp. 2284-2292 (2001)
- G. Sarkisov and D. Tikhonov "Martynov–Sarkisov integral equation for the simple fluids" Journal of Chemical Physics 99 pp. 3926-3932 (1993)
- G. A. Martynov, G. N. Sarkisov and A. G. Vompe "New closure for the Ornstein–Zernike equation" Journal of Chemical Physics 110 pp. 3961-3969 (1999)
- Gari Sarkisov "Approximate integral equation theory for classical fluids", Journal of Chemical Physics 114 pp. 9496-9505 (2001)