Numerical adiabatic potentials of orthorhombic Jahn-Teller effects retrieved from ultrasound attenuation experiments. Application to the SrF2:Cr crystal

A methodology is worked out to retrieve the numerical values of all the main parameters of the six-dimensional adiabatic potential energy surface (APES) of a polyatomic system with a quadratic T-term Jahn-Teller effect (JTE) from ultrasound experiments. The method is based on a verified assumption that ultrasound attenuation and speed encounter anomalies when the direction of propa- gation and polarization of its wave of strain coincides with the characteristic directions of symmetry breaking in the JTE. For the SrF2:Cr crystal, employed as a basic example, we observed anomaly peaks in the temperature dependence of attenuation of ultrasound at frequencies of 50-160 MHz in the temperature interval of 40-60 K for the wave propagating along the [110] direction, for both the longitudinal and shear modes, the latter with two polarizations along the [001] and [110] axes, respectively. We show that these anomalies are due to the ultrasound relaxation by the system of non-interacting Cr2+ JT centers with orthorhombic local distortions. The interpretation of the ex- perimental findings is based on the T2g (eg +t2g) JTE problem including the linear and quadratic terms of vibronic interactions in the Hamiltonian and the same-symmetry modes reduced to one interaction mode. Combining the experimental results with a theoretical analysis we show that on the complicated six-dimensional APES of this system with three tetragonal, four trigonal, and six orthorhombic extrema points, the latter are global minima, while the former are saddle points, and we estimate numerically all the main parameters of this surface, including the linear and quadratic vibronic coupling constants, the primary force constants, the coordinates of all the extrema points and their energies, the energy barrier between the orthorhombic minima, and the tunneling splitting of the ground vibrational states.Comment: 8 pages, 3 figure

Energy Release During Disk Accretion onto a Rapidly Rotating Neutron Star

The energy release L_s on the surface of a neutron star (NS) with a weak magnetic field and the energy release L_d in the surrounding accretion disk depend on two independent parameters that determine its state (for example, mass M and cyclic rotation frequency f) and is proportional to the accretion rate. We derive simple approximation formulas illustrating the dependence of the efficiency of energy release in an extended disk and in a boundary layer near the NS surface on the frequency and sense of rotation for various NS equations of state. Such formulas are obtained for the quadrupole moment of a NS, for a gap between its surface and a marginally stable orbit, for the rotation frequency in an equatorial Keplerian orbit and in the marginally stable circular orbit, and for the rate of NS spinup via disk accretion. In the case of NS and disk counterrotation, the energy release during accretion can reach $0.67\dot{M}c^2$. The sense of NS rotation is a factor that strongly affects the observed ratio of nuclear energy release during bursts to gravitational energy release between bursts in X-ray bursters. The possible existence of binary systems with NS and disk counterrotation in the Galaxy is discussed. Based on the static criterion for stability, we present a method of constructing the dependence of gravitational mass M on Kerr rotation parameter j and on total baryon mass (rest mass) m for a rigidly rotating neutron star. We show that all global NS characteristics can be expressed in terms of the function M(j, m) and its derivatives.Comment: 42 pages, 12 figures, to appear in Astronomy Letters, 2000, v.26, p.69

A Model of Technical University Students’ Creative-Project Activities’ Systemic Commitment to Their Self-Development and the Experimental Verification of Its Effectiveness

The urgency of the need to develop a model of the systemic commitment of creative-project activity of technical university students to their self-development is due to the fact that the reserve possibilities of this type of teaching, research and professional activities from the perspective of the systemic commitment to self-development of the students’ competitiveness remain insufficiently investigated in the theory and practice of teacher education. In this regard, the article presents the main components of the model of systemic commitment of the creative-project activity of technical university students to their self-development, as well as the results for its implementation in practice of higher professional education. The presented components of the model in the article (objectives, contents, methods, learning and educational environment) are working for the ultimate goal − for self-development of professional creativity, self-development of the competitiveness of a student as a prospective specialist. The results of the article can be used by administrators and faculty members of higher education institutions. DOI: 10.5901/mjss.2015.v6n2s3p12

Processing results from drill hole Pomorsk-1 in the Pechora Sea, south-east Barents Sea, central part of the Pomorskaya structure (Report 6166, Murmansk)

Project 4/86-88 Study of lithologic-facial composition of rocks, correlation of sections, and compilation of reference collections of Mesozoic-Paleozoic deposits from the Barents and Kara Seas based on drilling materials. Reasons for drilling: 1. Comprehensive study of properties, composition and lithologic-facial features of sedimentary rocks from the geological section in the Pomorskaya structure. 2. Obtaining information for stratification of the section. Technical results: The hole was drilled from 16.08.1985 till 14.11.1985. It has penetrated the section of 2750 m and stopped in Early Carboniferous deposits. 237 samples have been collected. Scientific results: 1. Comprehensive lithologic and paleontological studies of drill samples from the hole have allowed to reveal lithologic features and to carry out detailed lithologic and stratigraphic sequence from Early Carbonaceous to Quaternary sedimentary rocks. 2. From 2567 to 2750 m Carboniferous deposits are mainly carbonaceous and composed of limestones, dolomites, silicified limestones, rarely - of argillite bands. Upward (through the intermediate Early Permian carbonaceous-clayey series) they are changed by Permian-Triassic, Jurassic-Cretaceous and Neogene-Quaternary terrigenous deposits composed of alternation of clays, argillites, sandstones and siltstones with rare coaly bands. 3. On matter composition and facial characteristics the deposits of the section correlate well with coeval deposits from the Peschanoozerskaya (Kolguev Island) and Dresvyanskaya (Timan-Pechora region) areas and the adjacent continental part of the Timan-Pechora province. 4. The rocks are characterized by higher degree of catagenesis than coeval ones from the Peschanoozerskaya area

Processing results from parametric drill hole VNIIO-1986-NGul-01 at the North-Gulyaevskaya Area (Report 6171, Murmansk)

Project: 4/86-88 - Study of lithologic-facial composition of rocks, correlation of sections, and compilation of reference collections of Mesozoic-Paleozoic deposits from the Barents and Kara Seas based on drilling materials. Area of drilling: Pechora Sea (South-East Barents Sea), the near-arch part of the North-Gulyaevskaya structure. 890 km from Murmansk and 210 km to the north-east from Naryan-Mar. Reasons for drilling: 1. Comprehensive study of properties, composition and lithologic-facial features of sedimentary rocks from the geological section. 2. Obtaining information for stratification of the section and its allocation with geophysical sections. 3. Comparison of the section in study with earlier studied geological sections on the shelf and on land, study of regional variations of deposits and thicknesses of stratigraphic units. 4. Ascertainment of peculiarities of geological sections uncovered by marine drill holes, their dissection and correlation. Study of composition of Mesozoic-Paleozoic deposits, making of reference rock collections. Technical results: The hole was drilled from 31.07.1986 till 16.10.1986. It has penetrated the section of 3072 m and stopped in Late Carboniferous deposits. Scientific results: 1. Comprehensive lithologic and paleontological studies of drill samples from the hole have allowed to reveal lithologic features and to carry out detailed lithologic and stratigraphic sequence of the section composed of (from down to up) Late Carboniferous limestones, Early Permian carbonaceous-clayey series, and then Permian-Triassic, Jurassic-Cretaceous and Neogene-Quaternary terrigenous deposits. 2. For the first time in a section of a marine drill hole the hiatus in the Late Carboniferous deposits has been demonstrated. Kasimovian deposits are absent in the section. 3. Detailed characteristics of sediment matter composition have been done. Limestones of the Moscovian (Late Carboniferous, Pennsylvanian) formed in conditions of a mobile marine shoal. Late Permian terrigenous series formed in conditions of a near-shore shoal of a regressing sea and a low-lying deltaic plain. Early Triassic sandy-clayey deposits are chiefly continental. 4. The rocks are characterized by high degree of catagenesis. 5. From the Late Devonian till the Late Jurassic the North-Gulyaevskaya structure had a form of a double-plunging anticline. 6. On matter composition and facial characteristics the deposits of the section correlate with coeval marine deposits and deposits of the adjacent continental part of the Timano-Pechorskaya province