THEME01-3-1030-99/2003

Next theme	Prev. theme
to field of reseach	to contents

01-3-1030-99/2003

Priority:
Status:

1
In-progress

Theory of Condensed Matter

Leaders:

N. Plakida
V. Priezzhev

Scientific Programme:

Multi-particle models of solids taking into consideration strong electron correlations, electron-lattice and spin interactions to describe spectra of quasiparticle excitations, phase transitions and kinetic phenomena in solids. In equilibrium and nonequilibrium media with strong correlations such as liquids and nuclear matter the processes of multifragmentation, clusterization in phase transitions and the influence of surface effects on properties of clusters. In the theory of superconductivity, nonstandard mechanisms of pairing in metal-oxides, the problem of bipolaron stability in a polaron gas environment, the influence of strong electric fields and temperature gradients on elastic, magnetic, and thermal properties of granular superconductors. For the study of mechanisms of phase transitions caused by charge, orbital, and magnetic ordering in magnetic semiconductors and in metals with a large magnetoresistance, experimental data obtained at the Frank Laboratory of Neutron Physics, JINR, by neutron scattering and the

SR method will be used.

Nonlinear problems in multi-particle theory will be studied by using modern methods of the renormalization group theory, the inverse scattering problem, fractal geometry, and the conformal field theory. The main subjects of the study are integrable systems, equilibrium systems of the statistical mechanics and dissipative systems far from the thermodynamic equilibrium. The aim of these investigations is to reveal the common properties of the multi-particle systems associated with the ideas of self-similarity and universality.

The microstructure of amorphous state will be studied in the framework of the theoretical model where topological disorder is introduced via arrays of disclination dipoles and loops. The thermal properties of disclinated media are of primary interest. The electronic spectrum of carbon materials, fullerenes and nanotubes, will be examined within the field-theory model adapted to account for nontrivial geometry of these nanostructures. The model of random Josephson junction arrays will be studied and applied for the description of the high-temperature granular superconductors.

In the theory of finite quantum systems, local and low-dimensional states of matter obtained in modern experiments will be investigated. In particular, properties of quasiparticles in mesoscopic systems and the Bose-Einstein condensation in atomic traps will be studied.

Expected main results in 2001:

Calculation of spin susceptibility in manganites within the ferromagnetic Kondo model with orbital degeneracy. Investigation of superconducting mechanism in the periodic Anderson model allowing for Kondo effect and interorbital tunneling of coupled d- and f-electrons. Calculation of transport coefficients in doped cuprates and explanation of anomalous thermoelectric power in mercury cuprates and correlated oxides. Development of the superexchange theory and calculation of magnetic properties of NaV₂O₅ compound: spin-wave spectrum and EPR spectra.
Development of an integrable theory of avalanche processes. Derivation of the Bethe-ansatz equations for the one-dimensional avalanche model for periodic boundary conditions. Analysis of derived Bethe-ansatz equations in the thermodynamic limit and evaluation of finite-size corrections for the proof of the equivalence to the KPZ class of universality.
Calculation of a contribution to the thermal conductivity and the specific heat due to disclination dipoles of various configurations. Investigation of the influence of topological defects on the electronic properties of fullerenes and nanotubes. Derivation of a quasiclassical expression for the spin-tunneling rate in an alternating magnetic field and examination of an effect of the spin tunneling on the localization-chaos processes.
Calculations of the energy and effective mass of the electron confined to the asymmetric quasi 2-dimensional quantum well with the electron-phonon interaction taken into account. Study of distinctions between electron properties in the holon-spinon approach to the high-T_c and conventional BCS theory. Investigation of the interatomic potential dependence in ⁴He on the pressure on the basis of the experimental dispersion curves for the maxon-roton excitations. Description of the Bose-Einstein condensate, in particular the dynamics of the coherent multi-component mixtures as well as calculations of corrections to the Hartree-Fock-Bogoliubov approximation.

List of Activities
	Activity or project	Spokespersons	Principal researchers
1.	Strongly Correlated Systems	N. Plakida G. Repke
			W. Kleinig A. Kuzemsky V. Moskalenko V. Oudovenko J. Schmelzer V. Yushankhai
2.	Dynamic Systems: chaos, integrability and self-organization	V. Priezzhev
			L. Alexsandrov V. Mel'nikov V. Inozemtsev T. Ivanova E. Ivashkevich A. Povolotskiy V. Plechko K. Rerikh P. Zhidkov
3.	Disorded Structures: glasses, topological defects, nanostructures and Josephson junction	V. Osipov
			E. Kochetov S. Krasavin S. Sergeenkov
4.	Mesoscopic and Coherent Phenomena in Quantum Systems	M. Smondyrev V. Yarunin
			E. Bukina A. Cherny A. Chizhov V. Dubovik A. Shanenko V. Yukalov

Participating Institutes and Organizations

Armenia	YerPhI (Yrevan)
Azerbaijan	IP (Baku)
Belarus	IMAP (Minsk)
Belgium	UIA (Antwerp)
Brazil	Univ. (Brasilia, Sao Paulo)
Bulgaria	US, ISSP (Sofia)
Canada	CU (Montreal)
Czech Repablic	NPI (Rez)
France	CNRS (Marseille), Univ. (Nice)
Germany	TUD, IFW (Dresden), Univ. (Bremen, Humburg, Leipzig, Rostock), UNIDO (Dortmund), GMU (Duisburg),TU (Magdeburg), MPIF (Stuttgart), TUCW (Braunsweig)
Hungary	KFKI (Budapest)
ICTP
India	TIFR (Bombay)
Ireland	DIAS (Dublin)
Italy	Univ. (Catania, Salerno)
JINR	LHE, FLNP, LIT
Poland	UJ (Cracow), IP AMU (Poznan)
Romania	INFIN-HH (Bucharest)
Russia	KIGICh, LPI, MEPI, SINP MSU, PFUR, SRC RRC KI, SMI (Moscow), IMP (Ekaterinburg), ISU (Irkutsk), PSU (Perm), VIHPP (Troitsk), POMI (St. Peterburg), VSU (Voronezh)
Slovak Repablic	IP (Bratislava), IEP (Kosice)
Slovenia	Univ. (Ljubljana)
Switzerland	PSI (Villigen)
Taiwan	IP ASN (Taipei)
UK	Univ. (Cambrige)
Ukraine	NSC KIPT (Kharkov)
USA	CUNY (New York), UR (Rochester)
Uzbekistan	PTI (Tashkent)
Vietnam	IP NCSP (Hanoi)
Yugoslavia	INS "Vinca" (Belgrade)

Next theme	Prev. theme
to field of reseach	to contents

Theory of Condensed Matter

Leaders:

Scientific Programme:

List of Activities

Participating Institutes and Organizations