Igor P. Omelyan

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A revised version of the quaternion approach for numerical integration of the equations of motion for rigid polyatomic molecules is proposed. The modified approach is based on a formulation of the quaternion dynamics with constraints. This allows to resolve the rigidity problem rigorously using constraint forces. It is shown that the procedure for(More)
A novel approach is developed to integrate the equations of motion in many-body systems of interacting rigid polyatomic molecules. It is based on an advanced gradient-like decomposition technique in the presence of translational and orientational degrees of freedom. As a result, a new class of reversible phase-space volume preserving fourth-order algorithms(More)
  • I R Yukhnovskii, M V Tokarchuk, I P Omelyan, E M Sovyak, R I Zhelem
  • 1997
State of radioactive and nuclear safety of the object \Shelter" is analysed. Dynamics of active particles in glassy nuclear magma is suggested to be investigated with the aid diiusion equations taking into account radioactive transformations. The simplest model for the system \glassy nuclear magma{water" is formulated and therefore density prooles of active(More)
The main forms of nuclear fuel remaining inside the \Shelter" object and the main interrelated factors of nuclear and ecological danger are considered. Processes of interaction of fuel containing masses with water are analysed on the basis of experimental data. A statistical model for the description of radioactive elements is proposed. The pair structure(More)
An Enskog-Landau kinetic equation for a many-component system of charged hard spheres is proposed. It has been obtained from the Liouville equation with modified boundary conditions by the method of nonequilib-rium statistical operator. On the basis of this equation the normal solutions and transport coefficients such as bulk κ and shear η viscosities,(More)
  • I R Yukhnovskii, M V Tokarchuk, I P Omelyan, R I Zhelem
  • 2012
The object \Shelter" at Chernobyl nuclear power plant contains a lot of radioactive materials. Aqueous medium increases their mobility so that dangerous elements are persistently penetrating into environment with ground water. This situation and recent measurements are discussed. The egress is supposed to have a diiusion nature. A model for the diiusion(More)
The phase behavior of Ising spin fluids is studied in the presence of an external magnetic field with the integral equation method. The calculations are performed on the basis of a soft mean spherical approximation using an efficient algorithm for solving the coupled set of the Ornstein-Zernike equations, the closure relations, and the external field(More)
The magnetic phase transition in a Heisenberg fluid is studied by means of the finite size scaling technique. We find that even for larger systems, considered in an ensemble with fixed density, the critical exponents show deviations from the expected lattice values similar to those obtained previously. This puzzle is clarified by proving the importance of(More)
A new leapfrog integrator of rotational motion. Abstract A new algorithm is introduced to integrate the equations of rotational motion. The algorithm is derived within a leapfrog framework and the quantities involved into the integration are mid-step angular momenta and on-step orientational positions. Contrary to the standard implicit momentum approach(More)