50 th birthday of Ihor Omelyan
These days a renowned Ukrainian scientist, leading researcher of the Department of Nonequilibrium Processes of the Institute for Condensed Matter Physics (ICMP) of National Academy of Sciences of Ukraine, doctor of physics and mathematics Ihor Omelyan celebrates his 50th birthday.
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| Veröffentlicht in: | Condensed Matter Physics |
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| Datum: | 2011 |
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| Sprache: | English |
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Інститут фізики конденсованих систем НАН України
2011
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| Zitieren: | 50 th birthday of Ihor Omelyan // Condensed Matter Physics. — 2011. — Т. 14, № 4. — С. 47001: 1–2. — англ. |
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2017-06-10T19:54:11Z 2017-06-10T19:54:11Z 2011 50 th birthday of Ihor Omelyan // Condensed Matter Physics. — 2011. — Т. 14, № 4. — С. 47001: 1–2. — англ. 1607-324X https://nasplib.isofts.kiev.ua/handle/123456789/120057 These days a renowned Ukrainian scientist, leading researcher of the Department of Nonequilibrium Processes of the Institute for Condensed Matter Physics (ICMP) of National Academy of Sciences of Ukraine, doctor of physics and mathematics Ihor Omelyan celebrates his 50th birthday. en Інститут фізики конденсованих систем НАН України Condensed Matter Physics Personalia 50 th birthday of Ihor Omelyan Article published earlier |
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50 th birthday of Ihor Omelyan |
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50 th birthday of Ihor Omelyan Personalia |
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50 th birthday of Ihor Omelyan |
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50 th birthday of Ihor Omelyan |
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50 th birthday of ihor omelyan |
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2011 |
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English |
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Condensed Matter Physics |
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Інститут фізики конденсованих систем НАН України |
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These days a renowned Ukrainian scientist, leading researcher
of the Department of Nonequilibrium Processes of
the Institute for Condensed Matter Physics (ICMP) of National
Academy of Sciences of Ukraine, doctor of physics and
mathematics Ihor Omelyan celebrates his 50th birthday.
|
| issn |
1607-324X |
| url |
https://nasplib.isofts.kiev.ua/handle/123456789/120057 |
| citation_txt |
50 th birthday of Ihor Omelyan // Condensed Matter Physics. — 2011. — Т. 14, № 4. — С. 47001: 1–2. — англ. |
| first_indexed |
2025-11-24T18:42:37Z |
| last_indexed |
2025-11-24T18:42:37Z |
| _version_ |
1850486532262068224 |
| fulltext |
Condensed Matter Physics, 2011, Vol. 14, No 4, 47001: 1–2
http://www.icmp.lviv.ua/journal
Personalia
50th birthday of Ihor Omelyan
These days a renowned Ukrainian scientist, leading re-
searcher of the Department of Nonequilibrium Processes of
the Institute for Condensed Matter Physics (ICMP) of Na-
tional Academy of Sciences of Ukraine, doctor of physics and
mathematics Ihor Omelyan celebrates his 50th birthday.
Ihor Omelyan was born on December 20, 1961 in the city
of Lviv. In 1979 he entered the Physics Department of Ivan
Franko Lviv State University. Having graduated from the
University in 1984, he started his scientific activities in the
Lviv Division of Statistical Physics of the Institute for The-
oretical Physics (in 1990 this Division was transformed into
the ICMP).
Early studies of Ihor Omelyan dealt with the statistical
theory of metal systems. In particular, at that time, he de-
veloped in collaboration with Prof. Markiyan Vavrukh the
method of calculating the equilibrium structure distribution
functions of electrons in metals taking into account the ef-
fects of polarization. New fruitful period in Ihor Omelyan’s
research activities started in 1986, when he together with
Mykhailo Tokarchuk started the investigations of nonequilibrium processes in dense gases and
liquids based on a model kinetic equations of the revised Enskog theory. In 1988 Ihor Omelyan
together with D. Zubarev, V. Morozov and M. Tokarchuk proposed the concept of a consistent
description of kinetic and hydrodynamic processes in dense gases and liquids within the framework
of nonequilibrium statistical operator method. Based on it, the kinetic equation of the revised
Enskog theory for hard spheres system and the kinetic Enskog-Landau equation for charged hard
spheres system were derived consistently for the first time. The normal solutions of these equations
were found as well. These results are of great importance in modern statistical theory of nonequi-
librium processes. In this approach, Ihor Omelyan together with Mykhailo Tokarchuk proposed the
kinetic equation for the system of particles with the multistep potential of interaction, for which
the Boltzmann H-theorem was also proved. For the case of weak nonequilibrium processes, the
normal solutions of this equation were found and analytical expressions for transport coefficients
were obtained. A number of these results underlay the Ph.D. dissertation by Ihor Omelyan entitled
“Transport coefficients and correlation functions in dense gases and liquids” (under the supervision
of V. Morozov and M. Tokarchuk), which he successfully defended in 1991.
Starting from the 90-ies Ihor Omelyan works intensively in the field of development of com-
puter calculations methods (molecular dynamics, Monte Carlo simulations) and its applications to
the study of structural and dynamic properties of liquids. During 1993–1994 Ihor Omelyan and
Ihor Mryglod developed a computer-adapted version of a generalized collective modes approach
for simple fluids. For the first time, numerical calculations of generalized coefficients of bulk and
shear viscosity, heat conductivity as well as the dynamic structure factor and “current-current”
time correlation functions were carried out for Lennard-Jones liquid within a wide region of val-
ues of wave-vector and frequency using a higher-mode approximations and taking into account
both hydrodynamic and kinetic modes. Nowadays these fundamental investigations have become
a standard in calculating the dynamic characteristics of simple liquids within the framework of
generalized molecular hydrodynamics. Ihor Omelyan extended the concept of computer-adapted
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theory and the approach of generalized collective modes to the investigation of dielectric proper-
ties of polar liquids. Simultaneous presence of translational and orientational degrees of freedom in
polar liquids leads not only to the appearance of additional correlations, consideration of which is
indispensable for describing the dielectric properties, but to essential changes in the behaviour of
transport coefficients. Ihor Omelyan showed that new types of collective excitations, for instance,
dipolarons for dipolar liquids, as well as optic-like librational modes appear in complex polyatomic
models of polar liquids. In 1997 I. Omelyan together with R. Zhelem and M. Tokarchuk developed
the generalized hydrodynamics of polar liquids with regard to electromagnetic fields. The basic
hydrodynamic, polarization and kinetic modes for TIP4P model of water were studied. Herewith,
generalization of the response field and the Ewald summation for the atomic models of polar liq-
uids, which explicitly take into account spatial distribution of charges within the molecule, was
implemented. The computer-adapted fluctuation formulas were derived for several statistical en-
sembles and the dielectric permittivity along with magnetic susceptibility for atomic models of
water were computed within a wide range of wave-vectors and frequencies.
Using the methods of decomposition, Ihor Omelyan carried out a complete classification and
suggested a detailed derivation of all the self-conjugated schemes for integration of the equations of
motion in a computer experiment up to sixth-order accuracy in the time step. Optimal algorithms
were found, which permit to improve the accuracy of integration by several orders of magnitude
with the fixed computer time used.
Ihor Omelyan together with I. Mryglod and R. Folk (Austria) developed the computer-adapted
theory for the study of equilibrium and dynamical properties of magnetic liquids. To quantitatively
describe the phase diagrams, they evolved the method of integral equations for the Ising and XY
spin fluids.
In collaboration with F. Hirata (Japan) and A. Kovalenko, I. Omelyan obtained important
results for spatially-inhomogeneous systems. Within the method of inhomogeneous integral equa-
tions, the gas-liquid profiles for a simple liquid were calculated, being in good agreement with the
results of computer experiment.
In due time, Ihor Omelyan suggested the generalization of the method of integro-differential
equations for investigation of microscopic structure of interphase boundaries in magnetic liquids.
In collaboration with I. Mryglod, R. Folk (Austria) and A. Kovalenko (Canada), I. Omelyan estab-
lished a possibility of the existence of liquid-liquid surface interface in the Ising fluid. The phases
have the same density as well as the same magnetization in absolute value, but opposite in sign.
The dependence of the structure of interphase boundary for a gas-liquid transition and of the sur-
face tension coefficient on the external magnetic field were studied as well. It was shown that this
dependence for the XY model can be nonmonotonous due to a nonmonotonous dependence of the
critical temperature on the field.
Most of these fundamental scientific results mentioned above underlay the doctoral thesis in
theoretical physics entitled “Statistical-mechanical modeling of properties of polar and magnetic
fluids” (scientific advisor I. Mryglod), which Ihor Omelyan successfully defended in 2010.
I. Omelyan carried out a number of important applied investigations related to the prob-
lems of diffusion of radionuclides at Chornobyl region. In particular, I. Omelyan together with
I. Yukhnovskii, M. Tokarchuk and R. Zhelem developed a statistical theory for description of ra-
dionuclides migration in soils and subsoil waters. Besides, Ihor Omelyan in collaboration with
I. Yukhnovskii, and I. Mryglod developed new methods for the study of submicron radioactive
dust dynamics in the air medium. Appropriate algorithms and programs suitable for obtaining the
long-term predictions were elaborated. It was shown that submicron dust radioactive particles can
remain in the air for years and are capable of migrating at distances of thousands of kilometers
before settling down.
Nowadays, Ihor Omelyan and Andrij Kovalenko, friend from the University times, work to-
gether on solving complicated problems of multiscale dynamics in complex fluids at the Institute
of Thechnology, Edmonton, Canada.
Editorial board of the CMP, colleagues and friends cordially congratulate Ihor Omelyan with
his first jubilee and wish him to stay in a good health, good mood, to enjoy solving the puzzles of
nature and of computer programs which he has been doing with great success up to now!
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