Choosing a density functional for static molecular polarizabilities

Coupled-cluster calculations of static electronic dipole polarizabilities for 145 organic molecules are performed to create a reference data set. The molecules are composed from carbon, hydrogen, nitrogen, oxygen, fluorine, sulfur, chlorine, and bromine atoms. They range in size from triatomics to 14 atoms. The Hartree-Fock and 2nd-order M{\o}ller-Plesset methods and 34 density functionals, including local functionals, global hybrid functionals, and range-separated functionals of the long-range-corrected and screened-exchange varieties, are tested against this data set. On the basis of the test results, detailed recommendations are made for selecting density functionals for polarizability computations on relatively small organic molecules

Hyperfine excitation of CN by para- and ortho-H2

Among the interstellar molecules, the CN radical is of particular interest since it is a good probe of cold dark molecular clouds, and especially prestellar cores. Modelling of CN emission spectra from these dense molecular clouds requires the calculation of rate coefficients for excitation by collisions with the most abundant species. We calculate fine- and hyperfinestructure-resolved excitation rate coefficients of CN(X2+) by para- and ortho-H2. The calculations are based on a new potential energy surface obtained recently from highly correlated ab initio calculations. State-to-state rate coefficients between fine and hyperfine levels of CN were calculated for low temperatures ranging from 5 to 100 K. The new results are compared to available CN rate coefficients. Significant differences are found between the different sets of rate coefficients. This comparison shows that the new CN–H2 rate coefficients have to be used for observations interpretations. We expect that their use will help significantly to have a new insight into the physical conditions of prestellar cores

Evolution of cracks in selvedge of the coal bed during its stationary working

Purpose. To study rupturing of the coal/rock seam selvedge by natural gas-filled cracks as phenomena that prepare and initiate sudden outbursts of coal, rock, and gas during the steady movement of the face. Methods. The work is based on theoretical studies, including methods of thermodynamics, statistical physics, and asymptotic analysis. Findings. A generalized Griffith’s criterion for the material rupture by a crack is applied to the selvedge part of a gas-saturated coal/rock seam during its stationary unloading. Originality. The kinetic theory describing processes of gas-containing materials destruction is developed using the example of rupturing the selvedge part of a coal/rock seam by natural gas-filled cracks. Practical implications. The criterion for changing the control parameters (reservoir gas pressure, crack dimensions, rock pressure, surface coal/rock energy, elastic modulus) is found at which spontaneous failure of the seam becomes possible. This allows to discuss the possibility of predicting sudden outbursts of coal, rock and gas.Цель. Исследование процессов разрыва краевой части угольного/породного пласта природными газонаполненными трещинами как явлений, подготавливающих и инициирующих внезапные выбросы угля, породы и газа при стационарном подвигании забоя. Методика. Работа выполнена на основе теоретических исследований, включающих методы термодинамики, статистической физики, асимптотического анализа. Результаты. Получен обобщенный критерий Гриффитса разрыва материала трещиной применительно к краевой части газонасыщенного угольного/породного пласта при его стационарной разгрузке. Научная новизна. Развита кинетическая теория процессов разрушения газосодержащих материалов на примере разрыва краевой части угольного/породного пласта природными газонаполненными трещинами. Практическая значимость. Найден критерий изменения управляющих параметров (пластового давления газа, размеров трещин, горного давления, поверхностной энергии угля/породы, модуля упругости), при котором спонтанное разрушение пласта становится возможным. Это позволяет обсуждать возможность прогноза внезапных выбросов угля, породы и газа.Мета. Дослідження процесів розриву крайової частини вугільного/породного пласта природними газонаповненими тріщинами як явищ, що підготовлюють та ініціюють раптові викиди вугілля, породи й газу при стаціонарному посуванні вибою. Методика. Робота виконана на основі теоретичних досліджень, що включають методи термодинаміки, статистичної фізики, асимптотичного аналізу. Результати. Отримано узагальнений критерій Гріффітса розриву матеріалу тріщиною стосовно крайової частини газонасиченого вугільного/породного пласта при його стаціонарному розвантаженні. Наукова новизна. Розвинено кінетичну теорію процесів руйнування матеріалів, що містять газ, на прикладі розриву крайової частини вугільного/породного пласта природними газонаповненими тріщинами. Практична значимість. Знайдено критерій зміни керуючих параметрів (пластового тиску газу, розмірів тріщин, гірського тиску, поверхневої енергії вугілля/породи, модуля пружності), при якому спонтанне руйнування пласта стає можливим. Це дозволяє обговорювати можливість прогнозу раптових викидів вугілля, породи і газу.Работа выполнена в рамках научно-исследовательс-кой темы НАН Украины “Массо-, теплоперенос и физика предвыбросных явлений в газонасыщенном трещиновато-пористом слоистом углепородном массиве”

Foreign Policy and the Age of Globalization

Book review: Fred Aja Agwu. 2021. Foreign Policy in the Age of Globalization, Polpulism and Nationalism. A New Geopolitical Landscape. Springer. 485 p. https://doi.org/10.1007/978- 981-16-3372-

Popularity of species of polypores which are parasitic upon oaks in coppice oakeries of the South-Western Central Russian Upland in Russian Federation

The article deals with research of popularity of polypores species (Polyporaceae sensu lato), which are parasitic upon living English oaks Quercus robur L. in coppice oakeries of the South -Western Central Russian Upland in the context of their eco-biological peculiaritie

Eco-morphologic Aspects of Differentiation and Identification of Species Armillaria mellea Sensu Lato in Coppice Oakeries of Belgorod Region for the Purposes of Exploitation of Natural Resources

The article deals with matters of differentiation and identification of species of the complex Armillaria mellea sensu lato in loco in coppice oakeries of Belgorod region in Russian Federation. On the basis of results of comparison of local ecomorphotypes descriptions and known descriptions of Armillaria mellea s. l. European species it was stated that in Belgorod region’s oakeries there are two species belonging to the complex Armillaria mellea s. l.: Armillaria cepistipes and Armillaria gallic

Formation of pupils” Creative Activity in out – of – school Institution.

Статтю присвячено вивченню проблеми формування творчої активності вихованців гуртків науково-технічного напрямку в умовах позашкільного навчального закладу через моделювання занять. Здійснено аналіз понять «активність», «творча активність». Висвітлено рівні пізнавальної активності вихованців. This article is devoted to study the a problem of formation of pupils’ creative activity in technical circles in out – of – school institution over the lessons” modelation. The analysis of the concepts of «activity», «creative activity» and the levels of cognitive activity of pupils are higlighted.Бабула Ірина Ігорівна, заступник директора з навчально-методичної роботи Калугіна Ірина Миколаївна, методист ЦНТТУ

Digitalization of Higher Education in 2021 – Challenges for University Students In Russia

Digital educational platforms emerged as an anticipated technological response to the need for the modernization of higher education. The digitalization of education was promoted at the state level as a strategy and an instrument to improve the quality and competitiveness of education. In 2020, the coronavirus pandemic accelerated the transition from the classroom to online-only, revealing the lack of purposeful online teaching methods, and insufficient digital competence among teachers. The authors analyzed publications by foreign and Russian researchers to highlight the common problems of higher education digitalization, including datafication, limited capabilities of digital educational platforms, and the changing role of the teachers in e-learning. The article focuses on students’ attitudes towards online education, and their voluntary or unwilling involvement in the digital educational environment, considering synchronous, asynchronous, and blended forms of learning before and during the pandemic. The achieved results suggest that such factors as the novelty and accessibility of online courses at Western universities initially served as a factor of attraction the students, inviting them to diversify their studies in their own creative way. However, increased stress and workload, various technical problems, tough teachers’ control on the one hand, and poor feedback, on the other, weakened the popularity of the digital educational environment. When asked to compare the pros and cons of online education, most students spoke in favour of maintaining the blended education format, as it allows for reducing the workload and – to some extent – enables the students to take control of their education trajectories. This work is intended for educators and researchers interested in the challenges caused by integrating digital technologies into traditional forms of education

A new ab initio potential energy surface for the collisional excitation of N2H(+) by H2

10 pags.; 14 figs.© 2015 AIP Publishing LLC. We compute a new potential energy surface (PES) for the study of the inelastic collisions between N2H+ and H2 molecules. A preliminary study of the reactivity of N2H+ with H2 shows that neglecting reactive channels in collisional excitation studies is certainly valid at low temperatures. The four dimensional (4D) N2H+–H2 PES is obtained from electronic structure calculations using the coupled cluster with single, double, and perturbative triple excitation level of theory. The atoms are described by the augmented correlation consistent triple zeta basis set. Both molecules were treated as rigid rotors. The potential energy surface exhibits a well depth of ≃2530 cm−1. Considering this very deep well, it appears that converged scattering calculations that take into account the rotational structure of both N2H+ and H2 should be very difficult to carry out. To overcome this difficulty, the “adiabatic-hindered-rotor” treatment, which allows para-H2(j = 0) to be treated as if it were spherical, was used in order to reduce the scattering calculations to a 2D problem. The validity of this approach is checked and we find that cross sections and rate coefficients computed from the adiabatic reduced surface are in very good agreement with the full 4D calculationsThis research was supported by the CNRS national program “Physique et Chimie du Milieu Interstellaire.” F.L. and Y.K. also thank the Agence Nationale de la Recherche (ANR-HYDRIDES), contract No. ANR-12-BS05-0011-01. We acknowledge Laurent Pagani for stimulating this work.Peer Reviewe