Asymptotics of the Hartree-type operator spectrum near the lower boundaries of spectral clusters
We consider the eigenvalue problem for a perturbed two-dimensional
resonance oscillator. The excitation potential is given by a Hartree-type
nonlinearity with a smooth self-action potential. We use asymptotic
formulas for the quantum averages to obtain asymptotic eigenvalues and
asymptotic eigenfunctions near the lower boundaries of spectral clusters
which are formed near the energy levels of the unperturbed operator.
A general method for determining the asymptotic
eigenvalues near the boundaries of spectral clusters
is given. As an example, the spectral problem for a
perturbed two-dimensional oscillator is considered.
The eigenvalue problem for the perturbed resonant oscillator is considered. A method for constructing asymptotic solutions near the boundaries of spectral clusters using a new integral representation is proposed. The problem of calculating the averaged values of differential operators on solutions near the cluster boundaries is studied.
Within the presented monograph for the first time statistical approaches, based on the self-consistent field theory, were presented for the theoretical description of the thermodynamic properties of the ion-molecular systems (electrolyte solutions, ionic liquids, dielectric polymers and metal-organic frameworks) in the bulk solution and at the interfaces with the account for their molecular structure. In the book one can also find a thorough analysis of the state of the art of the theory and modeling of the ion-molecular systems. The book can be used as a guideline for the physical-chemists, physicists and nanotechnologists, working in the area of theory and simulation of the ion-molecular systems, and can let them utilize the discussed approaches for the solving of the different tasks of the chemical thermodynamics and condensed matter physics. Therefore, the book is addressed to the specialists, working in the area of physical chemistry and condensed matter physics, as well as to senior students and PhD students of profile specialty.
A method based on the spectral analysis of thermowave oscillations formed under the effect of radiation of lasers operated in a periodic pulsed mode is developed for investigating the state of the interface of multilayered systems. The method is based on high sensitivity of the shape of the oscillating component of the pyrometric signal to adhesion characteristics of the phase interface. The shape of the signal is quantitatively estimated using the correlation coefficient (for a film–interface system) and the transfer function (for multilayered specimens).
Let k be a field of characteristic zero, let G be a connected reductive algebraic group over k and let g be its Lie algebra. Let k(G), respectively, k(g), be the field of k- rational functions on G, respectively, g. The conjugation action of G on itself induces the adjoint action of G on g. We investigate the question whether or not the field extensions k(G)/k(G)^G and k(g)/k(g)^G are purely transcendental. We show that the answer is the same for k(G)/k(G)^G and k(g)/k(g)^G, and reduce the problem to the case where G is simple. For simple groups we show that the answer is positive if G is split of type A_n or C_n, and negative for groups of other types, except possibly G_2. A key ingredient in the proof of the negative result is a recent formula for the unramified Brauer group of a homogeneous space with connected stabilizers. As a byproduct of our investigation we give an affirmative answer to a question of Grothendieck about the existence of a rational section of the categorical quotient morphism for the conjugating action of G on itself.
Let G be a connected semisimple algebraic group over an algebraically closed field k. In 1965 Steinberg proved that if G is simply connected, then in G there exists a closed irreducible cross-section of the set of closures of regular conjugacy classes. We prove that in arbitrary G such a cross-section exists if and only if the universal covering isogeny Ĝ → G is bijective; this answers Grothendieck's question cited in the epigraph. In particular, for char k = 0, the converse to Steinberg's theorem holds. The existence of a cross-section in G implies, at least for char k = 0, that the algebra k[G]G of class functions on G is generated by rk G elements. We describe, for arbitrary G, a minimal generating set of k[G]G and that of the representation ring of G and answer two Grothendieck's questions on constructing generating sets of k[G]G. We prove the existence of a rational (i.e., local) section of the quotient morphism for arbitrary G and the existence of a rational cross-section in G (for char k = 0, this has been proved earlier); this answers the other question cited in the epigraph. We also prove that the existence of a rational section is equivalent to the existence of a rational W-equivariant map T- - - >G/T where T is a maximal torus of G and W the Weyl group.