Jaroslav Ilnytskyi: Scientific Activity

Research Background

Published Papers

Participation in the conferences and symposia

Degrees and grants awarded

 

Research Background

My scientific activity started in 1985 when I became a post graduate student at the Institute for Theoretical Physics of Ukrainian Academy of Sciences (supervisors Prof. I.R. Yukhnovskii and Dr. M.P. Kozlovskii). My primary investigations were phase transitions in the Ising and n-component model using the collective variables (CV) method. This method was developed for spin systems by I.R.Yukhnovskii and collaborators. It combines the collective variables approach (developed previously for fluid systems) with the renormalization group (RG) ideas. One of the primary features of the CV method is that it is non-perturbative. The self-consistent way of performing the RG transformation in the CV method was developed (together with I.R. Yukhnovskii and M.P. Kozlovskii). This helps to avoid the problems with the choice of the RG parameter and with its influence on the final results.

Other studies in the scope of these problems were connected with performing perturbation theory within the CV method. This work continued the earlier works of I.R. Yukhnovskii, I.O. Vakarchuk, Y.K. Rudavskii and Y.V. Holovatch. The epsilon-expansion procedure, which has originated from the Wilson RG approach, has been used in the CV method. This allowed us to obtain stable and accurate results for the critical indices in second order in epsilon (together with M.P. Kozlovskii). The accurate comparison of the CV RG scheme with the Wilson RG approach is also performed. This was done by comparing different classes of diagrams in both cases. These results were included in my Ph.D. thesis "Collective Variables Method and the epsilon-expansion" (1994, supervisors Prof. I.R.Yukhnovskii and Prof. M.P.Kozlovskii).

Further investigations started in 1995 involve computer simulations of the phase transitions in the liquid crystalline materials. The lattice model of rotators interacting via the angular part of the Berne-Pechukas intermolecular potential has been proposed. As compared to widely exploited Lebwohl-Lasher model this model contains a parameter of molecular elongation a which is used to control the anisotropy of the potential. This model was studied by means of Monte Carlo simulations near its orientational phase transition mimicking the nematic-isotropic (NI) transition in liquid crystals. We obtain progressive strengthening of the order of this transition as molecular elongation increases. Reasonably good agreement is obtained for the order parameter jumps (for molecular elongation a=3,4) with the values observed in the experiments.

This model for molecular elongation a=3 was studied in greater detail in the presense of a 5% concentration of disordered quenched impurities, in which case we have observed a very weak first order transition. The Monte Carlo simulations were performed for four different lattice sizes and the finite-size scaling analysis and the Ferrenberg-Swendsen reweighting technique were applied to obtained data. We have discussed a shift of the transition temperature, a suppression of the latent heat and the maxima of the heat capacity and susceptibility due to the presence of impurities. A comparison of the simulation data with the experimental results for liquid crystals confined to silica aerogels and porous glasses also has been performed. This work is done in cooperation with S.Sokolowski (Faculty of Chemistry, MSC University, Lublin, Poland) and O.Pizio (Instituto de Quimica de la UNAM, Coyoacan, Mexico, D.F.).

The other studies have been started recently concern behaviour of the Gay-Berne model for anisotropic liquid with the presence of the matrix of quenched spherical centers of different size. Both hard and soft matrix-fluid interactions are considered and the influence of the matrix on phase behaviour of the system is studied (together with A.Kovalenko, Institute for Molecular Science, Myodaiji, Okazaki, Japan).

Published papers

Referred papers

  1. I.R.Yukhnovskii, Ja.M.Ilnytskyi, M.P.Kozlovskii. Application of the specific phase space division to investigation of the 3D Ising model (Proc. of the conference Modern problems of statistical physics, Kyiv, Naukova dumka, vol.2, pp.103-108, 1989, in Russian).
  2. I.R.Yukhnovskii, M.P.Kozlovskii, Ja.M.Ilnytskyi. On choosing of the renormalization group parameter in investigation of 3D Ising model, Ukrainian physical journal, vol.34, No.7, pp.1106-1110, 1989 (in Russian).
  3. Ja.M.Ilnytskyi, M.P.Kozlovskii, Theory of phase transitions by the collective variables method: accurate critical indices and detailed comparison with the other approaches. Condensed Matter Physics (Lviv), Iss. 5, pp.23-41, 1995, LaTeX.
  4. Ja.M.Ilnytskyi, M.P.Kozlovskii, I.R.Yukhnovskii. On the theory of phase transitions by collective variables method, International Journal of Modern Physics B, vol.11, No.8, pp.1009-1022, 1997.
  5. Ja.M.Ilnytskyi. A study of the nematic-isotropic phase transition in liquid crystals by Monte Carlo simulations of lattice models, Journal of Physical Studies, vol.1, No.2, pp.232-240, 1997, abstract, ps.
  6. Ja.Ilnytskyi, Modified Lebwohl-Lasher model for investigation of nematic-isotropic phase transition in liquid crystals, Mol. Cryst. Liq. Cryst., vol.323, pp.113-128, 1998, ps.
  7. S.Sokolowski, A.Patrykiejew, Ja.Ilnytskyi, O.Pizio, Replica Ornstein-Zernike Equations for Polydisperse Quenched-Annealed Fluids. Hard Spheres in a Polydisperse Disordered Hard Sphere Matrix, Journ. Phys. Chem. B, vol.103, pp.868-871, 1999.
  8. Ja.M.Ilnytskyi, NEMATIC-ISOTROPIC TRANSITION IN A WEAKLY DILUTED LATTICE MODEL: MONTE CARLO STUDY, Condensed Matter Physics, 1999, vol. 2, No. 2(18), p. 189-196, ps.
  9. Ja.Ilnytskyi, S.Sokolowski, O.Pizio, Nematic-isotropic transition in a lattice model with quenched disordered impurities. A Monte Carlo study, Phys. Rev. E, vol.59, No.4, pp.4161-4168, 1999, abstract, ps.
  10. Ilnytskyi J, Wilson MR, A domain decomposition molecular dynamics program for the simulation of flexible molecules with an arbitrary topology of Lennard-Jones and/or Gay-Berne sites, COMPUTER PHYSICS COMMUNICATIONS 134 (1): 23-32 FEB 1 2001
  11. Ilnytskyi JM, Wilson MR, Molecular models in computer simulation of liquid crystals JOURNAL OF MOLECULAR LIQUIDS 92 (1-2): 21-28 Sp. Iss. SI JUN 2001
  12. Earl DJ, Ilnytskyi J, Wilson MR, Computer simulations of soft repulsive spherocylinders MOLECULAR PHYSICS 99 (20): 1719-1726 OCT 2001
  13. Ilnytskyi JM, Wilson MR, A domain decomposition molecular dynamics program for the simulation of flexible molecules of spherically-symmetrical and nonspherical sites. II. Extension to NVT and NPT ensembles, COMPUTER PHYSICS COMMUNICATIONS 148 (1): 43-58 OCT 1 2002
  14. Cuetos A, Ilnytskyi JM, Wilson MR, Rotational viscosities of Gay-Berne mesogens MOLECULAR PHYSICS 100 (24): 3839-3845 DEC 20 2002
  15. Saphiannikova M, Radtchenko I, Sukhorukov G, et al., Molecular-dynamics simulations and x-ray analysis of dye precipitates in the polyelectrolyte microcapsules, JOURNAL OF CHEMICAL PHYSICS 118 (19): 9007-9014 MAY 15 2003
  16. Wilson MR, Ilnytskyi JM, Stimson LM, Computer simulations of a liquid crystalline dendrimer in liquid crystalline solvents, JOURNAL OF CHEMICAL PHYSICS 119 (6): 3509-3515 AUG 8 2003
  17. Wilson M. R., Ilnytskyi J. M., Parallel computer simulation techniques for the study of macromolecules, in Computer Simulations of liquid crystals and polymers, eds Pasini P., Zannoni C. and Zu(mer S., (Kluwer 2004), 335-356.
  18. Wilson M. R., Ilnytskyi J. M., Stimson L. M., Hughes Z. E., Computer simulations of liquid crystal polymers and dendrimers in Computer Simulations of liquid crystals and polymers, eds Pasini P., Zannoni C. and Zu(mer S., (Kluwer 2004), 57-78.
  19. Ivaneyko D, Ilnytskyi J, Berche B, et al., Criticality of the random-site Ising model: Metropolis, Swendsen-Wang and Wolff Monte Carlo algorithms, CONDENSED MATTER PHYSICS 8 (1): 149-162 2005
  20. Ilnytskyi J, Saphiannikova M, Neher D, Photo-induced deformations in azobenzene-containing side-chain polymers: molecular dynamics study, CONDENSED MATTER PHYSICS 9 (1): 87-94 2006
  21. Ivaneyko D, Ilnytskyi J, Berche B, et al., Static and dynamic critical behaviour of 3d random-site Ising model: Different Monte Carlo algorithms, JOURNAL OF MOLECULAR LIQUIDS 127 (1-3): 69-70 Sp. Iss. SI AUG 15 2006
  22. Ivaneyko D, Ilnytskyi J, Berche B, et al., Local and cluster critical dynamics of the 3d random-site Ising model, PHYSICA A-STATISTICAL MECHANICS AND ITS APPLICATIONS 370 (2): 163-178 OCT 15 2006
  23. M.R.Wilson, L.M.Stimson, J.M.Ilnytskyi, The influence of lateral and terminal substitution on the structure of a liquid crystal dendrimer in nematic solution: A computer simulation study, Liquid Crystals, 33, No.10, 1167-1175, October 2006

Preprints

  1. M.P.Kozlovskii, Ja.M.Ilnytskyi, I.V.Pylyuk. Free energy and other thermodynamical functions of the 3D Ising model below the phase transition point, Ukr. Acad. Sci., Inst. Theor. Phys.; Preprint ITP-85-107P, Kyiv, 1985 (in Russian).
  2. I.R.Yukhnovskii, Ja.M.Ilnytskyi, M.P.Kozlovskii, Investigation of the critical properties of 3D Ising model. Specific phase space division, Ukr. Acad. Sci., Inst. Theor. Phys.; Preprint ITP-87-17P, Kyiv, 1987 (in Russian).
  3. Ja.M.Ilnytskyi. Investigation of the critical properties of 3D Ising model by the specific phase space division. The higher basic distributions, Ukr. Acad. Sci., Inst. Theor. Phys.; Preprint ITP-87-150P, Kyiv, 1987 (in Russian).
  4. M.P.Kozlovskii,Ja.M.Ilnytskyi. Description of phase transition in systems with dimensionality close to four in the collective variables method, Ukr. Acad. Sci., Inst. Theor. Phys.; Preprint ITP-87-100E, Kyiv, 1988.
  5. M.P.Kozlovskii, Ja.M.Ilnytskyi. Non-universal thermodynamical characteristics of the Ising model with the dimensionality close to four in the collective variables method, Ukr. Acad. Sci., Inst. Theor. Phys.; Preprint ITP-88-69P, Kyiv, 1988 (in Russian).
  6. Ja.M.Ilnytskyi, M.P.Kozlovskii, The reexpansion procedure. Application to the asymptotical series of the perturbation theory, Ukr. Acad. Sci., Inst. Theor. Phys.; Preprint ITP-90-38U, Kyiv, 1990 (in Ukrainian).
  7. Ja.M.Ilnytskyi. Collective variables method and the epsilon-expansion, Ph.D. thesis, Lviv University, 1994 (in Ukrainian).
  8. Ja.M.Ilnytskyi. Investigation of nematic-isotropic phase transition in liquid crystals by Monte Carlo simulations of lattice models. Ukr. Acad. Sci., Inst. Cond. Matt. Phys.; Preprint ICMP-97-04E, Lviv, 1997. LaTeX, ps
  9. Ja. Ilnytskyi, S. Sokolowski, O. Pizio, On the nematic-isotropic transition in a lattice model with quenched disordered impurities. A Monte Carlo study, Ukr. Acad. Sci., Inst. Cond. Matt. Phys.; Preprint ICMP-98-33E, Lviv, 1997. abstract, ps

Abstracts of talks and posters

  1. Ja.M.Ilnytskyi, The Reexpansion Procedure. Application to the asymptotic series of perturbation theory (First Soviet-Polish Symposium on Physics of Ferroelectrics, Lviv, Ukraine, 1990, Abstracts, p.139).
  2. Ja.M.Ilnytskyi, M.P.Kozlovskii, Critical behaviour of the n-component model by the approximate renormalization group transformation (Modern Problems of Statistical Physics, Kharkiv, Ukraine, 1991, Abstracts, p.79).
  3. Ja.M.Ilnytskyi, M.P.Kozlovskii, Equation of state of one-component spin model in the 3D case (Ukrainian-French Symposium "Condensed Matter: Science and Industry" Lviv, Ukraine, 20-27 Feb.1993., Abstracts, Information, Participants, Lviv, 1993. p.238).
  4. Ja.M.Ilnytskyi, Study of the nematic-isotropic phase transition in liquid crystals by means of computer simulations of the lattice models (Seminar on Statistical Theory of Condensed Matter, Lviv, Ukraine, 1997, Abstracts, p.121).
  5. Ja.M. Ilnytskyi, A study of the nematic-isotropic phase transition in liquid crystals by Monte Carlo simulations of lattice models (MECO 22, Szklarska Poreba, Poland, 1997).
  6. Ja. M. Ilnytskyi, A study of the nematic-isotropic phase transition in liquid crystals by Monte Carlo simulations of lattice models (Intas-Ukraine Workshop on Condensed Matter Physics, Lviv, Ukraine, 21-24 May, 1998, Abstracts, p.93).
  7. Ja. M. Ilnytskyi, Investigation of the nematic to isotropic phase transition by means of the modified Lebwohl-Lasher model (NATO ASI "Advances in the Computer Simulations of Liquid Crystals", Erice, Sicily, Italy, Abstracts).
  8. Ja.Ilnytskyi, S.Sokolowski, O.Pizio, On the nematic-isotropic transition in a lattice model with quenched disordered impurities. A Monte Carlo study (The Annual Conference of the British Liquid Crystal Society, Durham, Great Britain, 29-31 March 1999, Abstracts, P41).

Participation in the conferences and symposia

Degrees and grants awarded

Last updated 27 Feb, 1998
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iln@icmp.lviv.ua