The low-temperature behavior of a diluted magnetic semiconductor ͑DMS͒ is studied theoretically in terms of low-energy effective spin excitations ͑spin waves͒, including randomness of the dopant distribution. Two branches of spin waves are found, and their dispersions are analytically expressed versus hole and dopant concentrations in the DMS. It is found that for low and moderately low hole concentrations the magnetization of the DMS increases with temperature ͑near T =0͒ according to the 3 / 2 power law, while for higher hole concentrations the coefficient of this dependence changes its sign. The contribution of the spin subsystem of the DMS to the heat capacity increases with temperature according to the 3 / 2 power law as in a typical ferromagnetic material. The spin-wave-induced dephasing of an exciton spin in a quantum dot ͑QD͒ embedded in a DMS is estimated and compared with the experimental data. A temperature-dependent energy shift of the QD exciton in a DMS host material is also determined, in agreement with experimental observations.

Analyzing the first equation in the BBGKY chain of equations for an equilibrium liquid-gas system, we derived the analytical expression for the atom work function from liquid into gas. The coupling between the atom work function from liquid into vacuum and the stability criterion of liquid in limiting points of the first type was shown (using I.Z. Fisher classification). As it turned out, Fisher's criterion corresponds to the condition of atomization. We have expressed the state equation in terms of the atom work function from liquid into vacuum and performed calculations of the limiting line of stability composed of limiting points of the first type for argon. Our model discovers an interesting effect of the negative atom work function: at a constant volume of liquid, on a temperature rise (also at a fixed temperature and decreasing specific volume of liquid) the atom work function drops and takes a negative value with a modulus that is significantly larger than the atomic thermal energy. We propose a new two-stage mechanism of sonoluminescence based on non-thermal processes in liquid in a state with a negative atom work function. The first stage includes the emission of atoms from the interior of the bubble into gas at hyper-thermal velocities. At the second stage, a collision of emitted flow takes place between the gas atoms along with the implosion of the central part of the bubble. As a result of the impact excitation, ionization and the subsequent recombination, a flash of electromagnetic radiation develops that can be seen in sonoluminescence experiments.

On the basis of the perturbation expansion for the electron gas energy in the third order to the electron{ion potential the pair and irreducible three{ion interaction potentials in metallic hydrogen are calculated. The irreducible potential of three{ion interaction has attractive nature at short interionic separation and oscillates at large ones. The anisotropic character of the three{ion interaction is shown. The potential relief of the ions pair relative to the third ion is constructed. This relief has some potential wells and valleys which connect them. The important role of the irreducible three{ion interaction in the formation of the local order in three-and four{ion clusters is shown. The potential relief of an equiangular ion triplet relative to the fourth ion is calculated. This relief has a deep potential well for the fourth ion at interionic separation corresponding to the interproton separation in the H2 molecule . The quasiclassical probability of the ion transition into this well is evaluated. The life time of the metallic phase of hydrogen relative to the tunneling nucleation of the H2 molecules is estimated.

Studies of the coronavirus SARS-CoV-2 spread mechanisms indicate that the main mechanism is associated with the spread in the atmosphere of micro- and nanodroplets of liquid with an active agent. However, the molecular theory of aerosols of microdroplets in gases remains poorly developed. In this work, the energy properties of aerosol nanodroplets of simple liquids suspended in a gas were studied within the framework of molecular theory. The three components of the effective aerosol Hamiltonian were investigated: (1) the interaction energy of an individual atom with a liquid nanodroplet; (2) the surface energy of liquid nanodroplet; and (3) the interaction energy of two liquid nanodroplets. The size dependence of all contributions was investigated. The pairwise interparticle interactions and pairwise interparticle correlations were accounted for to study the nanodroplet properties using the Fowler approximation. In this paper, the problem of the adhesion energy calculation of a molecular complex and a liquid nanodroplet is discussed. The derived effective Hamiltonian is generic and can be used for the cases of multicomponent nano-aerosols and to account for particle size distributions.